For Rabllu nd God bosses u need a party of 7 members( because more member = high damage = less time to kill).
And all members should be 165lvlers so that u can do high damage on bosses.
Preferred Party members:-
2 Holy Knight
2 Mages
3 Archers or warriors can be nyone but archers preferred
Except hks rest all players can have a hp bar of 4-5k nd defence of 500-600 nd put rest all points in attack to get high damage because god bosses have 1 shot kill so ur hp bar or defence wnt save u.
Now go to map nd mage can pan you near rabellu. The first thing is that one hk go nd put warat or reduce on rabellu. Now both hks go back nd other party members start hitting boss with their best skill. Hks make sure that they stay out of range of Boss nd keep rcing the party members when they die. Rc as fast as u can nd keep giving kw to the party members.
Rabellu sede after some time now mages have to sede fast and find the rabellu with bulb nd pan all there. Hks should keep watch that keep giving warat or reduce to rabellu after some time before its time run out else u wnt be able to recognise which boss u were killing.
Now after finding the correct boss keep hitting it nd then it sede find again nd repeat the same thing. Btw these bosses have huge hp so u need patience as they will take 15-20mins to die if ur damage is not high enuf.
For other god bosses u can do the same process and the advantage is that other bosses dnt sede.
Ny query then please ask i will try to clerify it asap.
Enjoy Killing god bosses.