Looking at World of Warcraft Arena Ranking, many of the top ranked warlocks have 2/2 Imp. Drain Soul. The only useful purpose in PVP is landing a killing blow with your dots+pet, so you can get 15% mana back without lifetapping.

I can't figure out why anyone would spend those talent points in a PVP build; some even neglect Imp. Life Tap entirely to get it. Is there some subtle glitch I'm missing that makes the talent worth taking? Maybe in 2v2 with a healer, you always get the killshot, so it's good mana regen?

Or is this actually for pve dps (the -10% threat)? I would have thought more of the top warlocks would respec for arena.

They probably picked it up for PVE purposes. If I was to respec for Arena alone, I would never get Imp DS over any of the other available affliction talents. The mana regen could be nice for a soul link lock playing the mana-drain game, but even then, I'd rather have the points elsewhere since if you kill somebody, the game is likely over anyways.

Also, it's doubly worthless because if you are playing a team of the same faction, you don't really 'kill' them so don't collect honor, experience, soul shards, a free shard back from Shadowburn, or the mana from Imp Drain Soul.

So no, I wouldn't pick it up in a solely PvP build. It's only purposes are for less downtime when grinding and PvE threat reduction.

depends on what you are calling a pvp spec, 41/x/x then thats more or less a PVE spec that you can PVP with especially in a 3v3 or 5v5 but if you are looking at 24/37/0 or a variant like that you probably wont see that in that spec.

When making your way down to UA, it's not unreasonable to pick up Improved Drain Soul on the way as a filler talent for use in raiding/farming, but it's not an optimal PvP talent.

Thanks. I was worried I was missing something. I agree about "if you killed something, you already won."