Slitherwisp

Flash spent years as a modifier bolted onto individual cards without a reason to collect them; this is the card that gave the keyword a reason to become its own deck. The reward is stapled directly to the mechanic: every spell that explicitly carries flash (the ambush blocker, the flash-in threat, the counterspell that happens to have the keyword granted or printed on it) becomes a two-for-one that also chips the whole table's life total. The trigger's precision does the balancing: it fires only on spells that have flash, not on everything cast at instant speed, so a bare Counterspell contributes nothing unless something has handed that spell the keyword. That specificity forces deckbuilding into a genuine hunt for flash cards, not just a stack of instants that happen to be castable on the opponent's turn. The body carries the tension: a 3/2 is a fragile thing to hang a card-advantage engine on, and it wants to enter on an opponent's turn, hold up interaction behind it, and convert a reactive posture into an accruing one. The trigger keys on casting, not resolving, so a countered flash spell still draws and drains: it cares only that you paid the cost and held priority. This is a design finally paying flash off directly, the way morph and cycling eventually earned engines of their own. The keyword had a home now, and the drain was the deed to it.