These are suggestions for affliction warlock runes and books. First there are some ideas that involve doing dps and then there are some that turns affliction more to support role giving ability to provide mana and off heal to more classes. Drain mana and health suggestions would be interesting thinking of existing runes and talents in my opinion.
DPS
All curses apply Curse of Agony on the target as well. (Someone else’s idea but I agree)
Dark Pact (affliction tree end talent): increases time for all current damage over time effects on target for 10 seconds and gives 2 stacks of Nightfall proc. Maximum stacks is 3.
Wandering plague: corruption and siphon life are inflicted to close mobs from the original target.
Increased chance to proc nightfall with number of damage over time effects on target including damage over time effects applied by your group.
Siphon Life increases chance to proc Nightfall and Shadow bolt increases duration of Siphon Life. Siphon Life always applies the effect of Curse of Shadow.
Pet uses spells that are needed by you or your group: Curse of Recklessness, Curse of Elements, Curse of Shadow. Demonology talents that improve demons would add how many you can apply (1/2/3).
Pets are given the same buffs as you have automatically
SUPPORT
Drain Mana is no longer channeled and has 15 second cooldown and gives mana for your group. Improved Drain Mana talent also affects the mana gained by group.
Drain Life gives % of health drained to your group.
Health Stone cooldown reduced to 1 minute but healing is given over time to your group. Improved Health Stone affects the amount healing given to others as well.
There are many Nightfall proc ideas here because I love the play style of Affliction with mostly instant cast dots and few casted spells with chance of a proc that enables you to change position slightly.