Commander Imoti, Celebrant of Bounty Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less
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I had zero ways to kill it in my 75, which I think is correct since how am I supposed reliably make colored mana with Stony Silence in play (three Glimmervoid)
Even if you're not setting up an easy infinite, Muxus still puts a bunch of gobbos on board, and attacks as a large threat itself
The battles didn't necessarily help you close out a game and were working against the on-board snowball
It sets up any of black's non-sacrifice synergies efficiently, and it's a flying 6/6 for some reason, so it poses a decent clock