Poison Dispels
Poison dispels are mandatory in dungeons that blanket the group with venom. Without one, the healer spends every global cleansing instead of healing.
Specs that bring poison dispels
Brewmaster Monk
Detox
Protection Paladin
Cleanse Toxins
Restoration Druid
Nature's Cure
Preservation Evoker
Expunge
Mistweaver Monk
Detox
Holy Paladin
Cleanse
Restoration Shaman
Poison Cleansing Totem
Feral Druid
Remove Corruption
Windwalker Monk
Detox
Retribution Paladin
Cleanse Toxins
Enhancement Shaman
Poison Cleansing Totem
Balance Druid
Remove Corruption
Augmentation Evoker
Expunge
Devastation Evoker
Expunge
Elemental Shaman
Poison Cleansing Totem