Sygg, River Cutthroat

The trigger condition is the whole design: not damage you dealt, not a creature dying, but any opponent dropping three or more life in a turn, from any source. That decoupling turns this from a beater into a payoff. It does not care how the life left: combat, burn, a fetchland crack, a painland tapped twice, the opponent's own Phyrexian-mana spell, a shockland entering untapped. The 1/3 body confirms the intent; this is a thing that survives a turn cycle and watches, not a thing that swings for the loss-of-life it rewards. Splitting every pip between blue and black is the second tell, letting the card slot into any deck running either color without locking the manabase to a particular pairing, which suits a creature whose only job is to convert pressure other cards are already applying into cards. The threshold and the once-per-turn ceiling do the balancing: three is high enough that a do-nothing board state yields nothing, low enough that any deck built to attack an opponent's life total clears it without trying. End-step timing matters too, since it counts the whole turn's losses, including life the opponent pays on their own turn while the engine sits there passively accruing. A passenger that turns an aggressive or attrition-based game plan into a stream of cards, asking only that the deck around it already wanted opponents to be losing life.