blisterpod - two guys for one mana, what's not to love. also extremely good for bringing back with Lilly to sack for extra damage
bloodsoaked champion - agressive one drop that can be sacked late game and brought back multiple times in a turn, but if it comes to that sacking this guy is a good choice
catacomb sifter- two bodies that can be grabbed by co-co, and the scry is just card selection
den protector - monster of a card, has decent evasion and canbring back cheap things to be sacked, planeswalkers, co-co's just a good card in general
lilly, heritical healer- can be fetched by co-co, creates another creature which you can sack when it flips, can recur things, if you ult you just win then and there by endlessly sacking things with zulport cutthroat on the field, also helps you get your combo pieces from the grave yard if they die
nantuko husk - sac outlet, can end the game extremely fast if unblocked, and can normally trade favorably with any of the good sack targets
onmath - ends the game, a swarm of 5/5's are really good, alternatively you can play and say the elementals for extra face damage to end
zulport cutthroat - key combo piece, helps against aggro match ups and will end up being the wind con in grindy games, and so you gain bonuses when you sack things
bone splinters - extremely efficiant kill card, espically with all the good sack targets thus deck runs
atarka's command- deal the finishing blow, play an extra land to get ahead/trigger omnath, give your guys extra damage if you have a on of them
co-co- fill your board with sac outlets/targets, also lets you play and flip lilly at instant speed, if you do it during your combat and his some good sack targets you can sack them to nantuko husk to deal all the damage, also gets zulport cutthroat
ob- trying as a two of, card draw engine, kill spell, and can soak up some damage from other creatures, the ult can finish someone off after you drain them alot
evolutionary leap - sack outlet, helps you get card advantage, can sack any of the good sack outlets go get more sack outlets while draining your opponent, scrying, and drawing cards