Succumb to the Cold

Stun counters rewired the arithmetic of the tap effect. A plain tap spell only rents a single turn: the creature untaps on its controller's next step, so you've spent a card to skip one attack. The stun counter intercepts that untap step, forcing each creature to waste an entire refresh clearing the marker before it can act again. This card runs that math against one or two of an opponent's creatures at instant speed, which is the lever that separates it from single-target predecessors like Frost Breath: for the same window, you can strand two bodies instead of one. That optional second target is what buys the flexibility. Against a lone threat it's a two-turn freeze; against a pair it can blunt a whole attack step, or lock down two would-be blockers ahead of your own swing. What it does not buy is card advantage: those creatures stay on the battlefield, so this is pure tempo, a spell that trades a card of yours to steal turns rather than to erase a threat. The counter also lingers as an ongoing tax rather than a one-shot: it punishes plans that lean on untapping for mana, for crewing a Vehicle, or for convoke, since every one of those uses wants the creature available and the stun counter keeps it home. Its best line is patience, holding for the moment both halves of the "one or two" clause are live rather than spending it as a reflexive removal stand-in.