Class: Warlock
Build: Shadow destruction (0/21/40)
Cast rotation:
Shadow bolt (SB) spam and curses (curse of shadows/elements/recklessness or curse of doom if the former are not needed/already taken care of). At lower gear levels it may be reasonable to include corruption. Enough lifetaps to support the mana cost of these spells.
Notes:
Curruption should only be used if its damage per casttime is greater than the dmg per casttime of SB.
Improved fel armor (via the talent demonic aegis) adds 130 spelldmg.
The mana cost of SB is reduced by 5% if you take cataclysm.
For sustained dps the mana per second used by SB/curses/corruption has to be equal to the mana per second gained by lifetap and other sources (shadowpriests, totems, blessing/judgement of wisdom, manapotions, ...).
Improved SB uptime depends on group composition and stats of other shadow DDs. It is 1-(1-x)^4 , where x is the fraction of direct damage shadow spells hitting the target, that proc the ISB debuff. If you neglect all other shadow DDs, x would be the critchance. But the resulting uptime would generally be too high because affliction warlocks and shadowpriests use more charges than they provide.
Important talents/skills:
Improved shadow bolt (+20% shadowdmg debuff on SB crit)
Bane (reduces SB casttime from 3 to 2.5 sec)
Ruin (100% crit bonus)
Devastation and backlash (together 8% crit)
Shadow&flame (brings coefficient for SB to 3/3.5+0.2)
Demonic sacrifice (sacrifice succubus for 15% more shadowdmg)
Set bonus:
2 piece T4 and the spellstrike set have a +dmg proc, 4 piece T4 is a rather small buff (and useless if you do not use corruption)
T5 boni are rather disappointing, 2 piece does nothing for us, 4 piece is a very small buff if you use corruption
T6 2 piece does nothing for our dps but the 4 piece bonus is very good (+6% SB dmg)
Additional proc items:
[Band of the Eternal Sage],
[The Skull of Gul'dan],
[Hex Shrunken Head],
[Darkmoon Card: Crusade],
[Icon of the Silver Crescent],
[Eye of Magtheridon],
[Scryer's Bloodgem]
The trinkets with temporary +dmg can always be used directly before the curse of doom (if used) because of the 1 min CD. The haste buff from The Skull of Gul'dan and temporary +dmg buffs from other trinkets can be active at the same time.
Talent point distribution
You need 21 points in demonology (for demonic sacrifice) and 40 in destruction (for shadow&flame). The exact distributions could look like
this.