Is Gnarlroot Trapper legal in Standard, Modern, and Commander?

Gnarlroot Trapper is legal in: Modern, Pioneer, Legacy, Vintage, Commander.

What type of card is Gnarlroot Trapper?

Gnarlroot Trapper is a Creature — Elf Druid. Its oracle text reads: "{T}, Pay 1 life: Add {G}. Spend this mana only to cast an Elf creature spell. {T}: Target attacking Elf you control gains deathtouch until end of turn. (Any amount of damage it deals to a creature is enough to destroy it.)"