I've tried sorting the deck by card type. Let me know what you think :)

On a small minor note, I personally separate Solemn Simulacrum and Coiling Oracle between draw and ramp.

I consider Coiling Oracle strictly draw, and sometimes you can ramp by drawing.

I consider Solemn Simulacrum strictly ramp, with the chance that he might die and draw you a card.

This is just personal preference, but otherwise I like it. It is a bit different from my own sorting, so this gives me ideas to play with.

Yeah. I've sorted them as both since they sometimes serve both functions.

got to run the deck a few times. I like how it protects from board wipes.

Hello friend, solid list. It seems pretty tight. I noticed Progenitor Mimic in the side, and I think it's solid enough for main board, with your commander, you can regrab targets with it, it's a very powerful card. maybe Perplexing Chimera out for it?

some other thoughts

Restoration Angel

Cloudshift

Tooth and Nail

Genesis Wave

Progenitor Mimic will probably find a home here, and I think Conjurer's Closet will go out. I'll play a few more games before I decide. Perplexing Chimera is a nice political card, so I think I'll keep it for now. Any other suggestions for what to take out for the Mimic? Restoration Angel is also a nice suggestion, I like reusable effects more than instants like Cloudshift (or Momentary Blink). I've seen some Roon-list run the angel, some not.

I've recently started to consider Stonecloaker. I'll check my spare cards and add it in my maybeboard if I have one. It will probably be useful in some matchups.

Hm perhaps Arbiter of Knollridge it is political, but it is known for slowing up games. Don't get me wrong, he's a fun card, but kind of a dead draw if you are at the highest life total, and you put everyone back on the throne. whereas the mimic is really good whenever you draw it, and it has nice synergy with your general.

I really like Stonecloaker, it's very efficient.

Also, compared to everything else, how do you feel about Trostani's Summoner? I used to play it in a similar bant deck, and it ended up getting the axe.

Arbiter of Knollridge is in my maybeboard only, so I can't cut it for the Mimic.

Trostani's Summoner has been great for me so far. I've heard of several people cutting it and others having the same experience as me: With one or two blinks it's often game. It also has synergy with Reveillark, Skullclamp and Aura Shards.

Overall, this deck looks pretty sweet, though I definitely have some recommendations. Since you asked for my recommendations, I'm going to be a bit more thorough than I usually am, and offer thoughts on quite a few cards. First, some general thoughts on Roon. There are many ways to build this deck, but I've personally gone with control, and my suggestions will be based from that mindset. This is because any win-con in which I'm trying to build an army of tokens is a bit slow (it would take several turns to actually have enough to kill someone) and while you're building up, you're very vulnerable. I found that by playing control, my win-con was more of just having control of the board, and that gave my opponents less time to react. Furthermore, in order to do this, everything has to be efficient, and be relevant almost as soon as it's played. With that in mind, here are some suggestions. Cuts are first, then the suggestions are broken into infinite combo (encase you want to avoid those) and non-combo.

Cuts:
Conjurer's Closet - This card takes several turns to pay off, but a single turn in EDH is a long time. A lot happens in one round of turns, and it's very likely that this card will get destroyed. Furthermore, I found that, when blinking creatures, having it at instant speed was magnitudes more powerful, and I moved over to that.

Venser, the Sojourner - This card seems like one of the most auto-include cards of them all. Everyone loves Planeswalkers that are perfectly on flavor, but this is just a worse conjurer's closet, because Planeswalkers almost always get killed in EDH. And if it doesn't get killed, then you shouldn't have a problem winning, as your playgroup needs to step it up. See conjurer's closet for more points.

Mistmeadow Witch - This effect is great. It's just another Roon. However, now Roon can't be tucked, and this ability costs 4 mana. That's far too slow.

Brago, King Eternal - If this has been good for you, then feel free to keep it, but I've always got the problem that I don't overextend, so I typically only have 1-3 creatures in play at a time for this to hit, and then this creature actually has to connect, and it often dies. In general, while other engines seem like they generate value, this almost seems like a win-more card. It's only really good if you're ahead.

Trostani's Summoner - This is expensive and relatively weak. There are multiple more powerful cards.

Champion of Lambholt - I don't know if this has been good for you, but It's juts a beater, and I don't play beaters, so I put it on the chopping block.

Fiend Hunter - This is not as good as several other creatures as a form of removal. See Gilded Drake, Nevermaker, or Duplicant.

Burgeoning/Mana Vault - So it looks like you took the ramp package of Dominus - Dreamcrusher Edition and made it in your colors and more budget. Here's the problem: you aren't drawing cards the way that deck does. Damia is a drawing powerhouse. You don't need Burgeoning and Exploration. Yeah, they're both good cards, but those hands when you get both are gonna suck, and if you don't get either, your other ramp should be fine. In general, I would cut Burgeoning, but if you agree to cut one, then you probably have more experience with them are better fit to choose. Also, Mana Vault is kinda a one-shot card. With this deck being a value generating deck that doesn't typically do anything too explosive, Mana Vault doesn't seem as good.

Swiftfoot Boots/Lightning Greaves - I would only run one of these to decrease your chance of a dead draw, and because the haste isn't all that relevant for you. Also, if you want to protect your creatures, consider Privileged Position or Asceticism.

Sea Gate Oracle - You saw my analyses of this. I would add that this is just a bit weaker than other cards in the deck, and that as you add more powerful effects, this just won't be up to par before too long.

Combo Suggestions:
Palinchron - You probably know about this card.
Time Warp - With Archaeomancer or Eternal Witness, this card can easily net you infinite turns.
Phyrexian Altar - Goes infinite with any 2 of Karmic Guide, Reveillark, or Saffi Eriksdotter.

Non-Combo Suggestions:
Survival of the Fittest - Obviously ridiculous.Parallax Wave - Not obviously ridiculous. This card is amazing. It protects your creatures from removal, lets you have them re-enter, and keeps opponents from attacking you. This thing is just a fantastic toolbox of options for Roon decks.
Birthing Pod - This is just nuts. In general, I don't lose games in which this sticks for even just three turns, especially if I'm playing a combo build of my deck. Compared to Conjurer's closet, for example, this is cheaper up front and far more powerful.
Portcullis - This has been amazing for me. It stops a lot of decks cold, and just completely prevents them from functioning. If you have Roon out first, then you can hit an opponents creature and stick it under the Portcullis when it re-enters. Basically, you just slowly generate value, while most other players can't do anything.
Gilded Drake - This is just incredible. Overall, this should be in every Roon deck who's owner has a copy. I understand that it's expensive though.
Evacuation - Gets around indestructible, is instant speed, and lets you use all of your ETBs again. Personally, I really like this card, and have found it to be very effective.
Eladamri's Call - In a creature based deck, this is fantastic. I see you cut it, but I would recommend putting it back in. I like what you replaced this with, but maybe something else should go.
Ghostly Flicker - Instant speed blink is very strong, and this hits two creatures. Also, it makes a fantastic synergy with Archaeomancer or Eternal Witness, functioning as a 3 mana Deadeye Navigator ability encase that gets removed.
Momentary Blink - This has been fantastic in general. The single blink is really nice, though underpowered for costing you a card. Things like Cloudshift simply aren't worth it, but the flashback, I think, makes this card worthwhile.
More counterspells! - This is always good. Dissipate, Dismiss, Voidslime, Counterspell, and Cryptic Command are all strong.

@Traveler247: Just to note, you can use Fiend Hunter to combo off with creatures greater than power 2. It requires a little set up, but does come in handy from time to time. Also, it matters which sac outlet you use in the combo.

I would think about Plasm Capture for a counter spell as well.

@obitus By creatures with power greater than 2, do you mean 2 or less? Because the only thing that's power dependent in Roon that I can think of is Reveillark, but then this is only really relevant if you're playing infinite combos. It is further worth noting if you're talking about combos that Fiend Hunter + Karmic Guide + A sac outlet goes infinite, though I just now realized it.

Traveler247: Great feedback, thank you for taking the time :) I have some questions and comments if you have the time to read/answer them:
Do you agree that Progenitor Mimic is a better alternative than Conjurer's Closet? I've been wanting to try it for some time.

I'm a bit on the fence about Trostani's Summoner. Some say it's not worth it, some say it's an MVP. It's 10 power for 7 mana, and with Roon or another blink-engine available it's 19 power for ~9 mana. It's also a target for Skullclamp, Reveillark and good with Aura Shards, and has won me several games.

Mana Vault was quite recently included, and I haven't had a change to use it yet. I'm thinking it's better when you take synergy with Brago, King Eternal and Seedborn Muse into consideration, but I'm not sure.

Do you think Sylvan Safekeeper is a reasonable alternative to Privileged Position or Asceticism? It cheaper. Is Ashnod's Altar an alternative to Phyrexian Altar? I think I have one somewhere.

Is there any cards in my sideboard you'd consider adding mainboard? I've added some more tonight: Nature's Claim, Pongify, Gift of Immortality, Beast Within, Chromatic Lantern, Garruk, Caller of Beasts, Body Double, Mystic Snake and Nevermaker.

@Traveler247: The combo would be dependent on the Karmic Guide and Reveillark loop. The set up could look something like this:

Ashnod's Altar + Karmic Guide + Reveillark + Fiend Hunter + Gilded Drake

Lets assume Gilded Drake is on the field, and you cast Fiend Hunter. Run the Karmic Guide and Reveillark loop through Ashnod's Altar and let Fiend Hunter is your second choice from Reveillark's trigger.

Now Fiend Hunter can enter the battlefield multiple times hence targeting any creature it wants. Namely you would target creatures with power greater than two because you can not fit them into your Karmic Guide and Reveillark loop.

@Indigoindigo:

I would not use Sylvan Safekeeper, you will lose a land unless you have the proper cards to bring back land from the graveyard.

Ashnod's Altar is cheaper than Phyrexian Altar, it also helps out with combos because you get mana out each creature. Phyrexian Altar allows you to color fix, which I think you don't need.

I would add Mystic Snake before I add any counter spell, you can blink Mystic Snake repeatedly.

Also, I would consider Body Double because it acts like an extra graveyard recursion. This card has saved me plenty of times in the past. You cast your main combo piece and take out a counter spell, then follow up with this guy to continue with your counter. Most opponents won't have back to back answers, although some do.

I would drop some of your land if your not too sure what to clearly cut.

@Indigoindigo

Progenitor Mimic vs Conjurer's Closet is interesting. I don't play Progenitor Mimic in this deck personally, because 6 mana is pretty high (so is 5), but it does seem better because it has an immediate impact, and it's more abuse-able.

Trostani's Summoner seems better now that you've described it here. I will say that while it might be a good include for your current build, it just isn't powerful enough for a 7 drop in my build. You may find as your deck gets faster that this card isn't efficient enough.

If you just added Mana Vault, then definitely leave it. It's extremely important to test new cards and ideas.

Sylvan Safekeeper is definitely not a replacement for Asceticism or Privileged Position. And Ashnod's Altar just gives infinite colorless mana while Phyrexian Altar gives infinite colored.

In your sideboard:
Nature's Claim is good, but creature density is important in this deck, so I would tend not to include this.
Creature removal that isn't Swords to Plowshares, Path to Exile, or a creature: Don't play it.
Beast Within is super helpful for me. Good to have an answer to Torpor Orb or Hushwing Gryff.
Nevermaker has been great for me.
Body Double and Mystic Snake are both strong.
The rest of those cards are iffy.

@obitus I understand that interaction. I was just referring to if you have Phyrexian Altar in play, Fiend Hunter in your GY, and Karmic Guide in hand: play guide, returning hunter, exile guide, sac hunter, guide returns, get hunter, exile guide, sac hunter, guide returns...you get the idea. It generates infinite mana.

In the context of combos for Roon, Phyrexian Altar is better than Ashnod's Altar because if they are both generating infinite mana, then Phyrexian Altar makes it colored. This isn't usually relevant, unless you've tapped out to make the combo happen, and you want to cast a Blue Sun's Zenith to kill someone. Ashnod's Altar is frequently better, but in this instance, the extra mana is irrelevant. It's there to both provide a combo and prevent your creatures from getting exiled. They are largely interchangeable though.

Mystic Snake is good, the only problem is if you don't have the engines to flicker it at instant speed, then that ability isn't as useful as it seems on paper. It is worth play though, and I agree with you that it's a pretty strong include.

Body Double also goes infinite with Reveillark.

@Traveler247: I am sorry I miss understood your comment then, funny thing is I just understand the infinite mana part after you posted your previous comment.

I will have to check out your roon deck as well and compare notes with mine, maybe I can borrow an idea.

Solid deck! +1

You could replace Ephara, God of the Polis with Soul of the Harvest, he cost more, but he's aways a creature and provide some more tramplin'

Also, Galepowder Mage is solid in blink because he leaves you the choice to disrupt or blink your own. I would remove Swiftfoot Boots for him, since blink is a form of defence in itself and you aldready have Lightning Greaves.

hope this may help you!

I used to run Soul of the Harvest but found that it wasn't worth the 6 mana. If it's removed in some way it's a bummer, and I often didn't draw more than 1-2 cards from it. Not good enough for the investment.

Galepowder Mage is OK, but it doesn't work for defence and has to attack to work. I know several people that doesn't run Brago, King Eternal because it has to attack, and Brago is way better. Haste for Roon is also really good.

some card suggestions:

Craterhoof Behemoth

Stonehorn Dignitary

Acidic Slime

Great Whale for combo with Deadeye Navigator

Karmic Guide

Rings of Brighthearth

Sundial of the Infinite

@Austenlhr Just gonna drop my thoughts on your suggestions as well.

Craterhoof Behemoth - This is a good finisher, but you shouldn't run it if you are playing heavier control or combo. This is more of a finisher for a tempo build of Roon.

Stonehorn Dignitary - This is OK. I find it extremely underwhelming, and typically run Spike Weaver if I need to deal with the opponent attacking.

Acidic Slime - This is an allstar, obviously, and is already in his list.

Great Whale - Palinchron is a lot better, and I think that adding a combo may make the deck more competitive than it's trying to be.

Karmic Guide - Also obviously and all-star and already in his list.

Rings of Brighthearth - This is interesting. It interacts Ok with Roon, but doesn't really have any other synergy. Illusionist's Bracers seem better if you want to go this route.

Sundial of the Infinite - This has a nice interaction with roon and several other effects, but I would question if it's powerful enough to merit play. The slot this card would take up could be filled by something that is just straight up more powerful.

Thanks for taking a look, Austenlhr, and thanks for providing input Traveler247.

Craterhoof Behemoth is probably good and another wincon. It's price is what's keeping me from including it, since I'm not spending any money on Magic at the moment.

Stonehorn Dignitary used to be in my list. I removed it from being boring, especially in casual 1v1-games with friends. Replaced with Spike Weaver.

Great Whale or maybe Peregrine Drake as a budget Palinchron? If I want to do infinite combos this might find a home here.

Rings of Brighthearth might be good. I'm trying to add cards that give me an immediate effect ("When this card hits the board, X happens"). This card reads "When this hits the board, I need to have an activated ability that I want to copy and 5 mana (3 to cast, 2 to activate) available that I don't want to use on other stuff". That is rare, and the reason why I cut the cards Illusionist's Bracers and Strionic Resonator a while back.

Sundial of the Infinite used to be in my deck. It's only conditionally good, and I don't think I used it once. Some decks use it, but I don't think it's good enough without a certain boardstate.

A friend of mine is selling some cards and these are the ones I might be able to buy. I'd love some advice on cards to buy for $30-40.

Ramp: Birds of Paradise, Bloom Tender, Lotus Cobra, Somberwald Sage

Clones / Steal: Gilded Drake (a bit on the expensive side), Phyrexian Metamorph, Clever Impersonator, Sakashima's Student, Mimic Vat

Draw: Consecrated Sphinx, Sphinx's Revelation, Blue Sun's Zenith

Removal / Protection: Duplicant, Profaner of the Dead, Qasali Pridemage, Austere Command, Privileged Position, Sylvan Safekeeper, Path to Exile, Resolute Archangel, Venser, Shaper Savant

Utility / Combo / Misc: Mirror Entity, Restoration Angel, Parallax Wave, Stonecloaker, Peregrine Drake, Mirri's Guile, Flash, Deranged Hermit, Crystal Ball

Land: Wooded Bastion, Mystic Gate, Flooded Grove, Minamo, School at Water's Edge, Boseiju, Who Shelters All.

Gilded Drake, Venser, Shaper Savant, Restoration Angel, Austere Command, and Minamo, School at Water's Edge are all very powerful and would fit nicely in the deck. Personally with your budget, I would do Gilded Drake (because you can use their deck against them) and Minamo, School at Water's Edge (more Roon activations).

The Phyrexian Metamorph and Clever Impersonator are also great 75% cards, but I'd personally prioritize the other cards above.

Got 6 new cards:
Birds of Paradise will replace Arbor Elf.
Parallax Wave will replace Leyline of Anticipation.
Gilded Drake will probably replace Champion of Lambholt.

I also got Lotus Cobra, Bloom Tender and Qasali Pridemage. They're probably good too, but I don't know what to cut for them.

Those changes are excellent, I really like them! With regard to the other three cards (Lotus Cobra, Bloom Tender, and Qasali Pridemage) I don't really like them in your deck. Honestly, you aren't running enough fetch lands for the cobra, and I feel like it's best for giving you mana when you are trying to combo out. If you add more fetches, then it might be good, and it might be worth testing now because it is strong, but I've never been happy with it outside of a powerful combo deck with a crazy land base. Bloom Tender is the best of these, it can tap for a lot, it's strong. Qasali Pridemage doesn't have an ETB effect, and that really limits it's viability, in my opinion. You already have quite a few answers for artifacts and enchantments that are much stronger in your deck.

Anyway, happy deckbuilding!