When equipped with Evil Spell:

Increases damage of Venom Swamp by 20%.
Increases damage of Conflagration by 40%.
Increases magical damage against enemies of every element by 20%.
Decreases variable cast time by 5%.

[iRO Description]
Set Bonus:
Evil Spell
Evil Vigor (Elemental Master)

increases Venom Swamp damage by 20%,
increases Conflagration damage by 40%,
increases magical damage against all property enemies by 20%,
reduces variable casting time by 5%.