Eat to Extinction was the best, but a little slow and has a bad habit of being milled. the deck can't handle anymore escape cards (and Polukranos is expensive).

I've tried Polukranos, Unchained, Pharika's Spawn, Eat to Extinction and Casualties of War.

Assassin's Trophy is the catch-all, while Mogis's Favor is the removal from the graveyard. The problem is finding the right removal package for the deck (and finding space for them). The deck has problem dealing with evasive and/or large creatures (very removal light with situational removal).Deathless Knight is a little hard to cast (but no more than escaping an Uro), but is super easy to recur and some decks just can't hand a 4/2 with haste every turn.The one I am thinking about is possibly Ghostly Pilferer. Too often I have Silversmote Ghoul in hand when I would prefer them in the graveyard. Something I do want to include is more self-discard.Uro, Titan of Nature's Wrath is still incredibly powerful, but almost all decks are prepared for him now (even when wearing a Demonic Embrace).I've seriously considered replacing them with either more removal or Skull Prophet (and maybe even Excavation Mole). In others they are just overcosted self-mill. Ashiok, Dream Render and Tamiyo, Collector of Tales are the two highest variance cards in the deck.They are also the reason no Narcomoeba (a free 1/1 flyer just isn't worth the slot against most decks). The lack of Prized Amalgam and another turn one mill play like Stitcher's Supplier is a big reason why. The deck is grindy, not explosive like other dredge decks.The bad mana base is also why only three Merfolk Secretkeeper // Venture Deeper as with only five untapped blue sources it is unlikely to get the dream draw of turn 1 Venture Deeper into Creeping Chill & Silversmote Ghoul (I did get it once though, it was nice).Fabled Passage is the all-star land of the deck since it can be looped with Glowspore Shaman and goes to the graveyard when cracked. But despite that I don't think the deck can afford to play more non-basics.

This is what I am currently planning on testing some more. I spent most of last night playing through a ton of different versions of this deck on Arena.

Dredge mtg, edh