Is Frogmyr Enforcer legal in Standard, Modern, and Commander?

Frogmyr Enforcer is legal in: Modern, Legacy, Vintage, Commander, Historic.

Frogmyr Enforcer

Q: What type of card is Frogmyr Enforcer?

Frogmyr Enforcer is an Artifact Creature — Frog Myr. Its oracle text reads: "Prototype {3}{R} — 2/2 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.) Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)"