Dromosaur

A passive 2/3 right up until blocks are declared, when the trigger rewrites it into a 4/1 for the rest of the turn. The whole card lives in that one line: the swing to four power is welded to a collapse to one toughness, and you never get to pick one without the other. On offense, it sheds toughness to punch through a blocker; on defense, it gains the reach to kill a midsize attacker while leaving itself one damage from dead. Because the drawback and the upside share the same trigger, it plays like a beater with a combat trick you cannot hold in reserve: every fight it enters becomes a question of whether four power matters more than three toughness this turn. Once it fires, any blocker that lands a single point finishes it, and a throwaway chump that simply eats four trades down well. It belongs to a late-1990s strain of red creature priced near a vanilla body and then handed an all-or-nothing combat ability in place of evasion or a clean buff. What it cannot do is bluff: the opponent knows exactly what happens the moment they block, so it works less as a threat to be feared than as a lever for forcing the trade you want on the turn you choose to commit it.