Stompy

Upon getting three items or pills that increase Isaac's size, he will create dust clouds when walking and have a chance to spawn rock waves around him upon taking damage.

Isaac can also crush rocks and other destructible obstacles by walking over them.

Pills

 * One Makes You Larger (each pill taken will count towards the transformation)

Trivia

 * This transformation and Adult are the only transformations that pills count towards.
 * This is the only transformation that doesn't add to Isaac's costume, and instead only changes his size and adds dust trails when he walks, as if kicking up dirt by stomping.