it's not expliot, just trick (i dont know if it was posted, but i didn't found that:P)
it's working for rbs what need quest to summo (like bumbalump, ashutar...)
1) u must do quest at 1st time
2) go to statuet or sth (place when u summon rb)
3) summon him (quest item will disappear)
4) u can hit rb now, but before he die u must leave pt, or some1 other must do last hit (u'll not get quest item what is needed to finish quest)
5) (DON'T DELETE QUEST) now u can summon that rb, without making quest again, until you or yours party will make last hit