Is Pollywog Symbiote legal in Standard, Modern, and Commander?

Pollywog Symbiote is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Pollywog Symbiote

Q: What type of card is Pollywog Symbiote?

Pollywog Symbiote is a Creature — Frog. Its oracle text reads: "Each creature spell you cast costs {1} less to cast if it has mutate. Whenever you cast a creature spell, if it has mutate, draw a card, then discard a card. *It always knew it was destined to be more than a frog.* Power/Toughness: 1/3"