Magus of the Abyss

The original effect lived on an enchantment that fired symmetrically: at each upkeep, the active player chose one of their own nonartifact creatures to lose, no regeneration allowed. Porting that engine onto a 4/3 body is a real shift in strategic axis. As a creature, the Magus now dies to the removal it invites, and it adds a clock the static version never had: a body that grinds the board down and then swings is a different threat than a passive lock. But the symmetry has a sting the enchantment shared and that easy framing tends to bury. The destruction still triggers on your own upkeep, and it targets a creature you control. There is no pointing it at the opponent on your turn. If the Magus is the only creature on your side, it has no choice but to destroy itself. Living inside this engine means fielding expendable fodder (or artifact creatures, which the trigger cannot touch) so that something other than the Magus feeds it each turn. The "of their choice" clause cuts in your opponent's favor on their upkeep: they sandbag their best threat and feed the trigger their chaff, which makes the Magus sharpest against decks that can only deploy one creature at a time and dullest against a wide board that can spare a body every turn. The bargain is the same one The Abyss offered, now mortal and now able to close.