Turtleshell Changeling
Lorwyn — uncommon
Creature — Shapeshifter
Turtleshell Changeling rulings:
2013-04-15: Effects that switch power and toughness apply after all other effects that change power and/or toughness, regardless of which effect was created first.
2013-04-15: Switching 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.