Finn and Jiji, Inseparable

Whenever you cast a Dog spell, create a 1/1
green Cat creature token.
Whenever you case a Cat spell, create a 1/1
white Dog creature token.
{r}{g}{w}, {t}: Finn and Jiji, Inseparable deals
damage to any target equal to the number of
Dogs you control. You gain life equal to the
number of Cats you control.