I'm not sold on Oblivion Ring (Utter End is more permanent), Spirit Link, Spirit Loop, Curse of the Forsaken, Whispersilk Cloak, Vampiric Link, or Blood-Cursed Knight. As for what to add, check out MagicalHacker - Oloro, Ageless Ascetic (WB) for more lifegain matters cards and my profile page for more staples. I'd personally like some more card draw, more board wipes, and maybe better ramp (Ive never liked 3-drop rocks except Worn Powerstone and Coalition Relic), but that's just me :)

Should I use extort critters? They didn't seem to work with Oloro and are mana intensive and might draw me more hate.

Updated the list with changes

If extort draws hate (I certainly wouldn't hate on someone with a bunch of extort critter so, but hey), then it's definitely not worth it. Especially because there are plenty of things you can play instead, including lifegain-related stuff. :)

What were the changes?

Added:

Day of Judgment

Wrath of God

Utter End

Read the Bones

Sign in Blood

Bloodgift Demon

Sorin, Lord of Innistrad

Orzhov Signet

Loxodon Warhammer

Polluted Bonds

Disciple of Bolas

Cut most of the recommended cards and a few others like Angelic Accord. I'm iffy on the single draw spells

I prefer Angelic Accord to Disciple of Bolas in this deck honestly.

Alright switched Disciple for Accord. I like how it's shaping up. Feels like I'm missing something though, like more Karlov evasion? Pestilence Demon plus lifelink is funny... Unspeakable Symbol can be hilarious.

Essence Harvest and Wall of Reverence seem like good fits too.

Wall yes, harvest meh imo

Took out Erebos, God of the Dead for Wall of Reverence. The wall is more in line with the theme. Erebos had a purpose with Oloro but with Karlov getting his damage on the life they gain might not matter.

I'm not overly fond of Obzedat, Ghost Council. To gain life I lose out on a 5/5 body and have to wait a turn. If I keep the body it has no synergy just a vanilla critter.

Are you running all the soul sisters? Darien, King of Kjeldor works really well with them.

He is nice and the triggers that would come from him would be funny. But without the sisters he is a 6 cmc token generator that requires damage done to me to do anything. I'll maybe him for now.

I think I need some more protection for Karlov. He is quite susceptible to spot cleaning and will be a big target. Think Swiftfoot Boots and/or Lightning Greaves? Would most likely take out Sign in Blood and Skeletal Scrying. Blind Obedience and Basilisk Collar perhaps should find a spot.

The two boots and Darksteel Plate are always solid when you wanna protect a commander. Mother of Runes is also good for white decks for that purpose.

More changes:

Obzedat, Ghost Council >>> Mother of Runes: gives evasion and protection for Karlov

Sun Droplet >>> Mind Stone: a little more ramp and possible draw

Sign in Blood\Read the Bones >>> Lightning Greaves \Swiftfoot Boots: Karlov protection

Thinking I should throw in Akroma's Memorial for good measure or is that too much of a "good stuff" card here?

I'm not sold on Akroma's Memorial, cause you don't have tons of creatures in here. Could you try putting Sun Droplet back in and taking out Debt to the Deathless?

M a g i c a l H a c k e r: What are your thoughts on Dark Tutelage and/or Divine Reckoning? The former I can see working well and is another cheap card draw. The downside is you don't know how much life you'll lose and can't get rid of it should you need to and you end up revealing the card. But in a life gain deck it's negative effect might be somewhat diminished. Divine Reckoning seems weak, as they'll save their biggest threat. Then again we get to keep a fat Karlov and then can exile what is left over. Another good thing about this card is that we can use it twice.

Sun Droplet back in, Debt to the Deathless out.

Should I still run Exsanguinate as well? It's a decent finisher and works well with Cabal Coffers but is terrible aside from mid to late game.

I thought Dark Tutelage was possibly playable up until the moment I played one lol. My recommended permanent draw triggers for this deck are Phyrexian Arena, Underworld Connections, Graveborn Muse, and Well of Lost Dreams. Those first three are all solid choices for any black deck, and the last one is just good in any lifegain deck. If you want some burst draw, my favorite for the deck will be Skeletal Scrying, which is so undervalued! If the exile cost is not your style, Damnable Pact works too, but it's sorcery speed. Another great draw card that works great in lifegain decks is Farsight Mask, which is good in any deck, especially lifegain decks that require more attacking creatures than usual.

As for board wipes, Toxic Deluge is probably the best ever board wipe of all time. In addition, Oblivion Stone can save your commander, and even Tragic Arrogance let's you choose what players keep.

Finally, Noble Purpose can work as another copy of True Conviction/Whip of Erebos. :)

Thank you kind sir. I'm also wondering if Polluted Bonds is worth it at 5 cmc. The ramp player most likely would have went off by the time it hits the board. But it does grant a Karlov trigger on each player's turn essentially.

I'm also contemplating adding a land destruction package. I think after establishing a few life gain triggers that tossing out an Armageddon could be quite devastating

Polluted Bonds is really good, but I know a lot of decks that will recover from MLD much faster than this deck. It's usually useful in aggro, but not in a deck as grindy as this one.

I like how Noble Purpose can stack with lifelink. Hopefully that doesn't get errated to lifelink anytime soon :) What to take out for it though?