I'd go along with sweller on the anti-clockwise drill bits, but if you round off a socket head (Allen) you can belt in a torx bit with hammer and that may work. Use a decent quality bit or it will probably just snap though. The hammering of the bit into rounded off Allen socket helps free the stuck thread. Another method I've had success with in the past is to tap a welding rod onto the bolt so it gets stuck, that heats the bolt up nearly red hot and then turn off welder leaving rod stuck to bolt and bend rod over,wind out bolt. Good luck!