Another way to seek revenge on players who have defeated you is to get them back via Rival list. This list keeps track of opponents who have beaten you. You get to attack them back, regardless of their level, just as many times as they had beaten you.
===How does do Boss Fights work?===Here the bosses of various territories are listed. You can defeat them to get some special rewards in the game. But in order to initiate attack you need some special items that can be gained from 'Loot' missions in their respective mission territories.