Patch 10.0.0 (2022-10-25): Re-added and redesigned as a row 4 class talent (was a level 20 Enhancement ability). Increases your attack speed by 15% for your next 3 melee swings after dealing a critical strike with a spell or ability.
Old: Melee haste effects lower the cooldown and global cooldown of your Stormstrike, Lava Lash, Shocks, Unleash Elements, and Fire Nova.
Patch 6.0.2 (2014-10-14): Redesigned. Melee haste effects lower the cooldown and global cooldown of your Stormstrike, Lava Lash, Shocks, Unleash Elements, and Fire Nova.
Old: After dealing a melee critical strike, your attack speed increases by 15%, and you gain 50% additional benefit from Haste granted by items. Lasts 15 sec, or until 5 melee attacks have occurred.
Patch 5.0.4 (2012-08-28): Additional attack speed reduced from 30% to 15%. Now also grants 50% additional benefit from Haste granted by items. Charges increased from 3 to 5. Changed from a tier 3 talent to a level 20 passive.
Patch 4.0.1 (2010-10-12): Now a Tier 2 talent, down from Tier 4. Now increases attack speed by 10/20/30%, up from 6/12/18/24/30%.
Patch 3.1.0 (2009-04-14): Now provides 5/10/15/20/25% haste instead of 10/15/20/25/30%.
Patch 3.0.3 (2008-11-04): Now grants the proper number of charges when it triggers.
Patch 3.0.2 (2008-10-14): Now increases attack speed by 15/20/25/30/35% for your next 3 swings after dealing a critical strike.
Patch 1.10.0 (2006-03-28): Your haste will now last only the intended next 3 swings.