couple of nights ago me and my friend where doing a boss battle in the tob of storms and i was deafeted and she wouldnd heal me so she won. i ported back to here and he was gone. i tried to swich realms but it woundnt let me! somebody said i had to wait like an hour before he would sommon again! it looks like later all have to do that 4 boss dungeon again.
Once a boss is defeated you have to wait 30 minutes for the dungeon to reset. Or you can change realms. But you have to change realms when you are outside the dungeon, not in it (e.g., exit, change realms, then go into the dungeon).