Which cards (preferably arts, forts, etc.) can protect my opponent's heroes? The only one I can think of is Altar of Incense.
Altar of Incense (E)
Type: Artifact • Brigade: None • Ability: None • Class: None • Special Ability: O.T. Heroes are protected from discard special abilities on evil enhancements. • Play As: Protect O.T. Heroes from discard abilities on evil enhancements.
