Knight of Dusk's Shadow

Lifegain hosers usually come stapled to something you'd rather not run: a global enchantment that does nothing to the board, a static effect on a bear-sized body that trades down the moment it's summoned. What's unusual here is how little the hate tax costs. The lifegain lock rides on an evasive attacker that pumps itself, so the card that shuts off your opponent's stabilization plan is also the card applying the pressure that makes lifegain matter in the first place. Menace means the two-mana body demands two blockers to stop, and the repeatable growth ability turns leftover mana in the late game into an ever-larger threat that keeps forcing bad blocks. The two halves reinforce each other: you're racing a life total your opponent can no longer pad, with a clock that scales as the game goes long. That's the design logic worth noting: a hate piece is only as good as the game plan it's attached to, and stapling "your opponents can't gain life" to an aggressive, self-sufficient threat solves the usual dead-card problem. Against decks with no lifegain, you still have a growing menace creature. Against the decks the hate is aimed at, you have a growing menace creature that also happens to be turning off their entire out.