Desperate Prayer where art thou?

[MongoJerry]

It's very efficient as you said, it's actually one of the few talents that taken to it's maximum gives you outright a 25% efficiency boost on the spell,

Well, not really, as I said above. If the mob lives less than 18 seconds, then you had no increased mana efficiency at all. Similarly, if the mob lives, say 30 seconds, you'll still have to cast SW:Pain on it twice whether you have Improved Pain or not, so again there's no improved efficiency. There's some increased mana efficiency here, but in real life it's much less than 25%. My two favorite uses for Improved SW:Pain is on mobs that are running away and on PvP situations where you want to damage someone running away or want to damage someone about to kill you as a last desperate act.