Serpentine Ambush

Overwriting base power and toughness is a subtler tool than the 5/5 headline suggests, because setting a value works in both directions. Grow a mana dork into a real attacker, or drag an incoming fatty down to five, regardless of what it started at; the number is fixed either way. That reset has a known ceiling: base-stat overwrites and +1/+1 counters live in different layers, so any counters already on the target still stack on top of the fresh 5/5, and a heavily loaded threat can push right through the shrink. What the spell does not do is strip abilities. Turning the target into a blue Serpent wipes its previous creature types, which can matter for a "creatures you control of a type" trigger or a tribal payoff keyed to the old type, but the creature keeps every keyword and static ability it had; a lord that pumps by name or by an ability rather than by its own creature type is untouched. So this is not the Turn to Frog school of erasing what a creature can do. It is a body-and-type rewrite, and the catch on all of it is duration: the change evaporates when the turn ends, so every use is a single-turn window, priced to swing a combat or resize a blocker before it lapses. The 5/5 is the pitch; the instant-speed reset and the type swap are where the play actually lives.