Infernal Denizen

Creature - Demon 5/7, 7B (8)
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 his or her 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.¹
Illus. Drew Tucker

Gatherer Card Rulings [Nov 2009]

• 10/4/2004: You must sacrifice the Swamps if you can. You can't choose not to pay if you have them.
• 10/4/2004: You should always have one creature for your opponent to take (i.e. the Denizen). If by chance you have no creature for your opponent to take, then they don't get one. Remember that taking a creature is optional so your opponent is not forced to take the Denizen.

Format Legality	Legal in Vintage, Legacy Banned in Extended, Standard
Printings (1/6)	Ice Age (Rare)