I don't come across this all that often, but it does drive me nuts when I'm casting a spell on one mob in a group (linked, or I've gathered multiple mobs) and that mob dies and my spell is cancelled.

Can we get a default secondary target within the engaged mobs, so if the targeted mob dies while I'm casting a spell it will automatically reassign my target to another mob and my spell will still go off? Maybe this should/could apply to only AOE spells.