Whitemane Lion

Flash
When Whitemane Lion enters, return a creature you control to its owner's hand.

Aluren

Any player may cast creature spells with mana value 3 or less without paying their mana costs and as though they had flash.

Rin and Seri, Inseparable

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, 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.