Kinda all up to the player, but I find that both Soul of the Harvest and Harvester of Souls are both extremely dependent on other creatures entering/exiting the battlefield. I opted to just put in Yavimaya Elder as it can sac itself, draw a card and grab two lands from the deck, thinning it out in the process. Even if you use another sac outlet or just let it die in combat, it still nets u 2 lands.

Kothophed, Soul Hoarder is another option for the "6-drop that draws cards"-slot. It costs you some life, but triggers from fetchlands and all the random artifacts and enchantments that go to the grave. Smothering Abomination is cheaper, but requires more commitment to sacrificing creatures.

@Emzed: you have to be careful with kothophed though because his triggers aren't optional.

Yeah, Emzed, I feel chirz2792 is right here. Though he's cool and all, I could see a board wipe in multiplayer really ruining my day. :)

Thanks for the suggestion, though!

I didn't say it was generally the right choice, just wanted to mention the card. If there are lots of creatures and effects that kill them, Harvester of Souls seems much better. But there might be situations where Kothophed is superior, namely if your life total is under little pressure and he gets the chance to draw cards from noncreature permanents or token creatures. Against generals like Titania, Protector of Argoth, The Gitrog Monster or Daretti, Scrap Savant, Kothophed could be quite powerful. You know your metagame best, so it's your call which card to play.

Added in a copy of Miren, the Moaning Well.

Notched a few more multiplayer commander kills for Meren. Deck's playing so solidly.

After tonight, I definitely feel like I want Agent of Erebos in the 100 somewhere.

Solid deck!

My only suggestion would be to switch out Thought Vessel ( don't quite see why you need no maximum hand size as you could just discard extra critters ) for any of your maybe board ( I'm partial to Buried Alive to get your graveyard toolbox the tools you need for the situation at hand).

paloflimdul, I like it!

I shall order my copy.

Buried Alive is truly a silly card. Similarly to it, Fauna Shaman deserves a mention for being another cool card. It's the 'fair' version of Survival of the Fittest, though being both a discard outlet and a creature tutor on a body is still extremely powerful.

I've ordered the following cards for potential inclusion in this deck:

Phyrexian Arena, Burgeoning, Buried Alive, Fauna Shaman, and Harvester of Souls.

I've made the decision to definitely take out Soul of the Harvest and put in Harvester of Souls. I feel this trigger will benefit me more and can be a better threat overall on both offense and defense.

Someone above mentioned taking out Thought Vessel and I think I may do that. I'm also getting more and more tempted to add Agent of Erebos to the main. I have gone through many matches now where exiling an opponent's graveyard could benefit me greatly. I have cards such as Bojuka Bog, Deathrite Shaman, and Scavenging Ooze to do similar things, but those creature can be a little slow at it. I think Agent's ETB effect can be quite handy to have at my end step.

Will need to figure out some other cards from the current 99 that could come out in favor of the cards I just ordered.

Just looking through, my impression of cards that may under-perform are Butcher of Malakir, Creakwood Liege, Deadbridge Chant (especially with Buried Alive and Fauna Shaman coming in, its role as graveyard filler might be overtaken), Garruk, Apex Predator, & Savra, Queen of the Golgari. If any of these cards have been performing well, then by all means keep them, but they seem the most likely problem cards in my mind. Scavenging Ooze is probably the weakest of the graveyard hate you currently run, if you wanted to limit the amount you use and just swap something straight out for Agent of Erebos.

Those are all great choices for additions, by the way. Phyrexian Arena is just an incredibly solid card, I'm always happy to see it. And yeah, Thought Vessel does the opposite of what you want to do most of the time.

Newest update as my ordered cards just arrived today. Thanks for the suggestions, Coucho_Marx (as usual) as well as paloflimdul. Here are my exchanges:

Skullclamp coming out, Phyrexian Arena coming in. Just a better draw engine, less work to do it.

Thought Vessel coming out, the new (and more affordable) Burgeoning reprint from Conspiracy coming in. If Thought Vessel was there for an extra mana, I think Burgeoning will do it better, especially as I play multiplayer a lot.

Soul of the Harvest coming out, it's ugly li'l brother Harvester of Souls coming in. There's more things dying in my games than necessarily coming in. Also, new guy will likely give me more than one card a turn and even cards on others' turns. Green dude will likely give me one card, maybe two, on my turn only.

Big Game Hunter coming out, Agent of Erebos coming in. Been thinking about bringing him in for too long now that I know it's meant to happen. There are good scenarios where exiling opponents GYs are a good thing, and Meren can make it happen a lot. I like Big Game a lot, he may come back at some point for a roster spot, but right now he's benched.

Glissa, the Traitor coming out, Buried Alive coming in. I don't need artifacts back from the GY that badly. She's so awesome on defense, but hey lack of ETB effects isn't always convenient.

Lastly, Scavenging Ooze coming out, Fauna Shaman coming in. I have a few cards now that exile GYs, and they do so with less mana investment. Don't need the life gain all that much, and Fauna could work well here, so we'll try her out.

Thanks for the ideas, chaps!

I wouldn't take out Skullclamp, the draw power is still too good and it helps getting counters for Meren. I would take out Deathreap Ritual because it's EXTREMELY conditional and it costs 4.

Sounds reasonable. I'll make the adjustment.

Took Meren out for a spin tonight in a 3-way Commander game between her, Sidisi, Brood Tyrant and Skullbriar, the Walking Grave. Won that one. Then we had a second match against Skullbriar, and Sidisi was switched out for Prossh, Skyraider of Kher. Won that one.

Meren and the graveyard shenanigans had all decks under severe lock down for pretty much the entirety of both games. All my creatures were the right utility at the right time, their ETB effects controlling what needed to be controlled. Spore Frog, you make so many people hate this deck. All-star across both games was definitely Buried Alive, finding me three tools I need to shape the game in my favor, no matter what the circumstances were tonight. Massacre Wurm is an amazing finisher when my opponents are at 20 or less life.

This deck is running so smoothly now and I'm finding that I'm never back-peddling too much with this deck...never sweating or too much on the defensive. This deck is packed with creatures, but make no mistake, this is a very controlling deck. Holy lock-down.

I'm looking forward to next week where we're arranging a 6-7 Commander multi-player game. Largest Commander game I've ever personally done, and Meren's gonna be front and center for me!

I'm on the fence about Burgeoning. I think it's a good card, but was a little sour on it tonight super-late in the game. The card would be amazing ramp in the beginning of the game, but towards the end, most players (myself included) aren't holding a whole lot of lands in our hands. I'm considering this is one of the first cards I may cut when determining which card from the new Kaladesh set would fit well within this deck.

Have you considered Eldritch Evolution? It's a cheap way to find the right creature, and sacrificing something isn't a big cost for you.

Have you considered Quillspike? He can do infinite damage with Devoted Druid. Wall of Blood has insane interactions with Disciple of Bolas, and Jarad, Golgari Lich Lord (also combos with the Quillspike for infinite damage).

As for cuts, perhaps Agent of Erebos? He's a meta call, though. Would also suggest possibly taking out Vulturous Aven and Savra, since Aven seems a tad underwhelming compared to cards like Phyrexian Arena. Savra seems underwhelming to me in general. But hey, if your deck is running smoothly, glad to hear! :)

Meren sounds a lot like my ex, love the description, +1 :D

How has Blade of Selves been working out for you? I'm thinking of adding it to my Meren deck. I'd love to equip Gray Merchant of Asphodel, crush my enemies, see them driven before me, and hear the lamentations of their women...

Hey, guys, thanks for the suggestions!

Emzed, Eldritch Evolution certainly fits the theme and mechanics of this deck, but it's functionality is somewhat sub-par for what I need it to do. I have a few creature-methods to tutor up other creatures like Sidisi and Rune-Scarred. Spells like Buried Alive and Entomb as well. Right flavor, but it's a little outclassed thus far.

paloflimdul, blade of selves has been amazing, given all the creature ETB this deck has going on. Never afraid to suicide attack either, just because Meren will give me the creature back again anyway. It's like a Strionic-Meren on steroids. Only time I didn't like it was when all other players were dead my multiplayer and had only one opponent left...but, hey, at that point the game's looking pretty good.

Triton, Quillspike looks fun with the druid, but that's really the only interaction with Quillspike. Though cute, I think it's too narrow. Wall of Blood looks like something I could put in my Oloro commander deck! And Jarad... I'll give him thought. He could be good.

Hey Loco, thank you for posting your deck and everyone for their comments! For a long time I didn't know how to refine my Meren deck. In short, it was a complete mess. I based some of my upgrades on your deck and will give you credit. Mine is just kitchen table fun but I hope you have time to see it!

Taking out one Burgeoning, adding in a Noxious Gearhulk.

Taking out Strionic Resonator and adding in Panharmonicon.

Removing Animate Dead, adding Liliana, Heretical Healer  ^Flip in its place.

maybe take out garruk instead of animate dead, more synergy with deck

tendouji, thanks for chiming in. This move thus far is just based on my last half dozen games. When I have Animate Dead my hand, it's just "ok." Hasn't done support amazing things. Realized with Liliana that, because she's a flip Walker, she's like a recurring Walker all day long. I see some value in that and am going to try it out in my upcoming six-man Commander tomorrow night. We'll see if she comes up. And Garruk....well I just love that planeswalker, lol.