I thought of another way to implement Chainspell that would increase RDM's DPS:

Chainspell - Ability - 90s CD: Reduces weaponskill cast time and recast time, spell cast time and recast time, and auto-attack delay by 50%, reduces damage by 40%, and require no cast time for 10s. Effect is lost if you use a weaponskill.

This is an overall gain by itself if you look at the math: (1 - 40% damage reduction) /( 1 - 50% cast time) = 60/50 = 1.2 for a 20% damage increase.

This also acts as a massive mana generator as well. You can alternate between Veraero/thunder for the duration and get 8-9 casts in for 44 black/white mana very quickly.