Baleful Eidolon

Bestow exists to solve the structural problem that aura-based aggression never quite cracked: the two-for-one a removal spell hands you when your buff and its host die together. The mechanic splits the difference by letting a card be an Aura first, then revert to a creature when the enchanted target dies, so the worst case is a 1/1 that traded a body for a card instead of nothing. This is the deathtouch slot of that cycle, and deathtouch is the keyword that makes the floor genuinely matter. As a plain creature it is a 1/1 wall that eats anything that swings into it; bestowed for its higher cost, it both pumps the host and lends it the same trade-everything-it-touches threat. That keyword transfer is the real work. A 1/1 that kills on contact is a fine blocker; a 4/4 attacker that destroys whatever blocks it is a different conversation. And when the host dies, the Spirit itself detaches as a creature again, keeping deathtouch on its own body: the buff was never a dead aura, because it was always a creature waiting to come back. That redundancy is the entire point of the bestow frame, here in its most defensive coloring, built so an aggressive black deck could commit to a buff without fearing the blowout that historically punished anyone who put an Aura on a creature.