I haven't tested this on softcore, but on hardcore this is a very deadly bug.
When blasting with cone shape on a warlock, you freeze. as in become completely unable to move, do anything ,even exit the game. Your client just freezes, however, the game and anything around you does not.
At first I thought it was my computer (as my party members could move around no problem and continue fighting when this happens but I am frozen and unable to act or move or do anything). However, one of my friends with a better computer than I have just had this happen to him (trying out a cone blasting warlock for the first time on hardcore). Luckily I was able to kill everything around him while he was stuck.
so uhm, yeah. something is VERY wrong with cone warlocks atm. It doesn't happen all the time (it almost seems tied to specific quests. It consistently happened to me in Magma Must Flow, and in the Lords of Dust, it happened to him in part 1 of the waterworks).
HALP!