Agent of Masks

The whole engine fires once a turn, on your upkeep, and that timing is the tell about what this card was built to be: not a finisher but a clock you set and ignore. One life drained per opponent, that much life gained back, every upkeep until somebody answers it. Against a single opponent the math is glacial; the design clearly assumes a table full of them, where the same trigger scales linearly with the number of players and the lifegain follows in lockstep. That makes the 2/3 body almost incidental: it is a chump-blocker stapled to an attrition tax, a little Orzhov drain that asks only that you keep it alive long enough for arithmetic to do the work. It sits in the long line of black-white extort-and-drain effects that turned slow, incremental life-swing into an archetype rather than a side benefit, the cards that win by making every turn cost the rest of the room a point. Nothing here is flashy, and nothing here is meant to be; the card's only ambition is to never stop, and to make removing it the opponent's problem rather than yours.