Level 30 defiler here.
On inc i land on the mob: fuliginous sphere(24 secs), degeneration(70 secs), revulsion (70 secs), comtamination (24 secs). I sustain both dots (sphere and contamination). The effect of all those dots and debuffs are important; they lower the total power of the mob or and hp, slow the mob, mob hits for alot less and do considerable dmg with 2 dots. I also do Vile imprecation (100 dmg nuke with massive debuff to cold fire disease poison resists, last 24 secs)
Warding is out of the question since i ALWAYS team with a caster and we do ancient crucible non stop (+12% total power regen HO) and that ward often end up breaking the HO. Since that HO uses a direct heal i dont need to use wards anyway. And i also feels that wards have been utterly useless ever since i got to level 20. Healing ritual adept3 has been my main form of healing.
Doing this HO non stop (and yes defilers are the best priest to open up this one with vile or our fast casting dots) and maintaining the dots/debuffs i often end up almost not healing except for the heal i have to do during the HO and then i finish the fight almost at full power because of this HO. Also the mobs is so severely debuffed that it deals like 50% of its normal dammage if not more (some mobs have innate huge strenght values and others dont). Also you have to note that the slow component of fuliginous and degeneration seems to stack (one is a dot and other is a pure debuff)...so pay attention to this.
So in short, defilers are very good healers when we play with HO and are by far the best damage dealers and mitigators but this doesnt invole the use of our useless wards.
Oubaro
level 30 defiler