Protean Hulk

The death trigger is the entire point, and the design is built around making the body irrelevant. You are not paying seven mana for a 6/6 Beast; you are paying it for a tutor that fires when the creature dies and drops the spoils straight onto the battlefield, so the deckbuilding game is finding the fastest way to kill your own card. The free-flowing "total mana value 6 or less" with no creature-count cap is what gives it combo elasticity: the same trigger can fetch a single value piece or a multi-creature engine that assembles a kill on the spot. The clause has no "may," no exile, no finality counter slowing the loop, so the engine wants to resolve the trigger at instant speed with the rest of the pile already accounted for. That open-endedness is exactly why it has been a perennial banlist resident in singleton formats: a single sacrifice converts one dead body into a precise board state, and in a deep enough pool that board is a deterministic win. Note the line a combo player has to thread: the creature must actually die, so a sacrifice outlet works while a flicker effect (which exiles and returns rather than sends to the graveyard) does nothing. The 6/6 is camouflage. The lasting design lesson is that the value of a death trigger is not what it returns but the precision of what it can fetch, and how little it asks you to pay for the search.