Is Infernal Denizen legal in Standard, Modern, and Commander?

Infernal Denizen is legal in: Legacy, Vintage, Commander.

Infernal Denizen

Q: What type of card is Infernal Denizen?

Infernal Denizen is a Creature — Demon. Its oracle text reads: "At the beginning of your upkeep, sacrifice two Swamps. If you can't, tap Infernal Denizen, and an opponent may gain control of a creature you control of their choice for as long as Infernal Denizen remains on the battlefield.{T}: Gain control of target creature for as long as Infernal Denizen remains on the battlefield."

Creature — Demon

At the beginning of your upkeep, sacrifice two Swamps. If you can't, tap Infernal Denizen, and an opponent may gain control of a creature you control of their choice for as long as Infernal Denizen remains on the battlefield.<br>: Gain control of target creature for as long as Infernal Denizen remains on the battlefield.