Poisoner's Apprentice

The infusion clause is the whole gate here: a 2/2 for three mana that does nothing on arrival unless you have gained life this turn by the time it resolves, at which point it fires a -4/-4 pulse that erases most creatures outright. That ordering is the interesting part. Unlike a card that gains you life as it resolves, this one just needs the lifegain to have happened by resolution, so the payoff is retroactive: you spend the earlier part of the turn setting up, and the Orc arrives to collect. It rewards a deck already leaking life triggers (drain effects, lifelink attackers, incidental gains) and punishes a deck that tries to slot it in cold, where it stays a vanilla body. The -4/-4 rather than a flat -X/-X or destroy is a deliberate ceiling: it clears the small and midsized creatures a lifegain shell tends to face, but leaves the genuinely large threats standing, which keeps the removal honest without a permanent-counter drawback. Because the debuff lands as an enters trigger, it can be blinked or recurred to re-arm, turning the conditional into repeatable spot removal in the right engine. The design lesson is that a conditional built around a resource you were already generating costs almost nothing to satisfy and reads as far more restrictive than it plays.