The Arcanum of Rapidity is a enchanted gem that will add a haste effect to either a head or leg item. This effect will not stack with other enchantments on the item.
Arcanum of Rapidity as a quest objective
- The Arcanum used to be needed for the special class-specific Zul'Gurub enchantments. However, the requirement was removed in Patch 1.11.
- The quest to get all Arcanums are repeatable.
- Attack speed increases do stack with each other, you can get two librams, a counterweight and haste to gloves enchant, and they all stack.
- "Haste rating" is now used instead of a straight percentage buff. According to Blizzard, items converted to the new rating system have no direct changes in their effects.