Alms Beast

A 6/6 for four mana is an absurd rate by any honest accounting, which tells you the lifelink clause is not flavor: it is the entire tax. The trick is who that lifelink belongs to. The keyword goes to whatever this Beast is fighting, on both halves of its combat. When it attacks, any creature that blocks it gains lifelink and recoups life equal to its own combat damage (a 1/1 chump nets the defender one life, not the Beast's full six). When it blocks, the attacker it is blocking gains lifelink and walks away with life equal to the damage it dealt. Either way, throwing this body into combat funds the other player. That inverts the usual instinct about a big attacker: instead of pressuring a life total, the Beast subsidizes whoever stands in front of it. The design is a genuine drawback creature in the lineage of Lord of the Pit and Phyrexian Negator, where the body is real and the leash is the point, except the leash here is racing math rather than an upkeep cost. Breaking the symmetry is the whole game: pump it into a one-sided kill, remove the blocker at instant speed, or give it first strike so the small body dies before it ever deals the damage that would feed its controller. Deathtouch does not help, since a trading blocker still connects and still drains. Left to swing and block as a vanilla 6/6, it is a liability dressed as a bomb.