That macro is absolutely incredible, thank you Vikterion.
That said, I took it one step further because I'm even more lazy than you guys, and I want to make sure that I *ALWAYS* receive the increased mana regen from getting the killing blow with drain soul, without having to manually stop my pet from attacking. You just remove the shard bags that you aren't using, for example I'm using "Box of Souls" so mine looks like this.
/cast Drain Soul(Rank 1)
/run local a=GetBagName(4); if a=="Box of Souls" then PickupContainerItem(4,GetContainerNumSlots(4)) DeleteCursorItem() else end
/run PetFollow();
I keep all my DOT's active, wand/drain life the mob down while VW tanks, and once it gets below 20ish percent I use this macro, which pulls your pet off guaranteeing you the killing blow and thus the improved mana regen.
Thanks to all of you that have contributed in this thread, made leveling a lot easier.