Cant be countered is a modest bump up in power, but it feels like a silver bullet against the oops
They know how to masterfully explore different points of view, including the observer's, to make the background even more valuable
(Artifact, battle, creature, enchantment, instant, kindred, land, planeswalker, and sorcery are card types.) Illustrated by Franz Vohwinkel Standard Not Legal Alchemy Not Legal Pioneer Not Legal Historic Not Legal Modern Legal Brawl Not Legal Legacy Legal Comp
And while he may only enable you to sacrifice one permanent per turn, team him with sacrifice engines like Viscera Seer, tokens or recurring permanents (like Bloodghast or the cat oven combo of Witchs Oven and Cauldron Familiar) to sacrifice, and drainers like Blood Artist and Mayhem Devil, and things snowball very fast