Cheapest priced copy (The List): $0.35 at Card Kingdom, near mint, their price list as of .
Turtleshell Changeling 
Creature — Shapeshifter · 1/4 · Uncommon · The List · #LRW-94
Changeling (This card is every creature type.)
{1}{U}: Switch this creature's power and toughness until end of turn.
Legal inCommanderModernLegacyVintage
Not legal inBrawlStandardPioneerPauper
2 printings · $0.35 to $2.99 at Card Kingdom
3 rulings from Wizards of the Coast
- 19 March 2021Because damage remains marked on a creature until the damage is removed as the turn ends, nonlethal damage dealt to a creature may become lethal if you switch its power and toughness during that turn.
- 19 March 2021Effects that switch a creature's power and toughness apply after all other effects, regardless of when those effects began to apply. For instance, if you target a 1/2 creature then give it +2/+0 later in the turn, it's a 2/3 creature, not a 4/1 creature.
- 19 March 2021Switching a creature's power and toughness twice (or any even number of times) effectively returns the creature to the power and toughness it had before any switches.