Seri, Immortal Companion

Partner with Rin, Eternally Faithful
Whenever you cast a Dog spell create a 1/1 White and Green Cat Spirit creature token.
Cats and Dogs you control have Lifelink, Vigilance, and get +1/+1
{3}{w}{g}{t}: Cats and Dogs You control get +3/+3 and gain Trample until end of turn