Can regenerate save a creature from "destroy all creatures"? What about "put all creatures on the bottom of their owners librarys"? Also "return all nonland permanants to their owners hand"?
Regenerate only saves creature from lethal damage or destroy effects. If its toughness is reduced to zero by -1/-1 abilities or spells it dies. Returning the creature to hand or putting it on the bottom of library isn't effected by regenerating the creature.