The only reason lately that I'll use these spells is to give my team time to get
the MOBs off me (Imp Protectors hit HARD!- and I once got Trapped behind
Skarlon's butt- not nice). This time window, plus the anti-taunt effect is
usually enough to let me get up and start casting again.

I usually will use DA first in a controlled area, where we know the spawns and
are not likely to get jumped. I'll use DB first when there are a few heavy
hitting MOBs that jump me (well okay, I'm trying to get either off- but DB seems
to work better, even with the longer casting time). This works especially well
when I throw a heal on our puller then will wait until the last possible moment
to cancel DB if I have to heal, or just med through until DB fades.