Shriveling Rot

Neither mode kills anything on its own. The first turns the board into glass: for the rest of the turn, any damage a creature takes (a combat strike, a burn ping, a deathtouch graze) destroys it instead of merely marking damage. The second is a payoff that fires on death, draining each dying creature's controller for its toughness. The card supplies the rule change and the punishment; you supply the damage. That separation is the whole design. Choose one and you are buying a single instant-speed effect that needs a board state already moving in your favor: a stalled ground you want to push an attack into, a ping you want to make lethal, a sweep already in progress that you want to bleed for. Pay the entwine cost and you get both clauses stacked, but the killing still routes through some external source of damage; entwine does not manufacture a wrath, it just means everything that does fall also costs its controller life. The tax is the brake. Stacking the modal cost on top of the base price is what keeps a two-trigger setup spell honest, since the payoff scales with how much damage you can already throw around. It is the rare black instant that does its work without naming a target, killing through other people's effects rather than its own, and that indirection is exactly why it asks for a plan built around it rather than a single button to press.