Mystery Booster 2

Legendary Creature — Dog Cat Scientist

All Cats you control are Dogs in addition to their other types.
All Dogs you control are Cats in addition to their other types.
Cats and Dogs you control have haste.

Rin and Seri, Inseparabler

Core Set 2021

Legendary Creature — Dog Cat

Whenever you cast a Dog spell, create a 1/1 green Cat creature token.
Whenever you cast a Cat spell, create a 1/1 white Dog creature token.
{R}{G}{W}, {T}: Rin and Seri deals damage to any target equal to the number of Dogs you control. You gain life equal to the number of Cats you control.