I think even on caster this guy is bit to good to not take especially on good old warlock as you will be toughest sob in your camping as initiate detect good and evil is means you are always knowing who to kill and who to spare plus having angel and fiend blood on you means you are on the dead or recruit list on every major player in the setting just look nephalem of diablo as even weakest nephalem is skilled enough to have legend of their own and most of them regularly invade deepest layers of hell to have a picnic.