Steam Vents [Guilds of Ravnica] Arena League 2001 {T}: Each player gains control

{T}: Each player gains control of all creatures they own

If Unbreathing Horde would be dealt damage

−7: Search your library for up to three artifact cards with different names

Chief Commander can't attack unless defending player controls an Island

it becomes an Aura with "enchant creature put onto the battlefield with Necromancy

Steam Vents [Guilds of Ravnica] Arena League 2001 {T}: Each player gains controlSet: Guilds of Ravnica Type: Land Island Mountain Rarity: Rare ({T}: Add {U} or {R}.) As Steam Vents enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped. "A massive new Izzet building project with an unstated purpose? Probably fine." Zija, Simic mutationist