some tools folks need to be aware of...
reverse drill bits- kinda a last resort, will drill with drive in reverse allowing the torque to loosen the bolt.
easy out set- (also called a bolt extractor) various shaped tool set to tap into the hole you just drilled but still couldnt get the bolt out. shaped so it grabbes the sides of the hole then use a wrench to turn the easy out. Kinda replaces the bolt head but stronger.
WD40- the ONLY thing I have found this often misused item, as a former gunsmith, usefull for is to loosen bolts and occaisionally cleaning metal/displacing water. Its terrible as a general lube. Apply liberaly over night if unable to soak the part.
Propane torch- heat the bolt to loosen any thing in the threads like loctite and try.
Hammer- tapping a bolt can shock the stuff locking the threads. not always usefull for loctite but can get the light rust loose. Dont use a dog gone maul, just a light ball peen.
HTH