Will and Monty, Rae's Boys

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}: Willie and Monty, Rae's Boys deals damage to any target equal to the number of Dogs you control. You gain life equal to the number of Cats you control.