Event Bosses
Events are time or condition specific boss fights within the dominion which can only happen once or a few times per void cycle. They're also where portals to the more difficult dungeons in the game are dropped from.
Spawning points for each of the 8 event bosses per dominion
When a new dominion opens, events bosses will spawn in a clockwise order from 1-8 (refer to picture above), with the first one spawning immediately. After the death of one event boss, the next will spawn 1 minute later.
The diagonals (1, 3, 5, 7) will spawn a random minor event boss: Ravana, Corrupted Skull, Great Eagle, or Crimson Lord. The same minor event boss can spawn multiple times during the same event rotation.
The edges (2, 4, 6, 8) will always spawn: Aspect of Legion, Aspect of Conquest, Aspect of Corruption and Aspect of the Void respectively in that order.
Aspects
Aspects are the manifestations of Darza's lieutenants in the Dominion. They spawn in the North, East, South and West sides of the dominion during event rotations. All four of them have to be defeated before players will be summoned to The Void, the domain where Darza resides.
Minor events
Minor events are event bosses that spawn in the Northeast, Southeast, Southwest and Northwest sides of the dominion during event rotations. Unlike the aspects, a random minor event boss is spawned and they are not location specific.
World events
World events are events that spawn in certain locations in the Dominion. They become active once certain conditions have been met.
Conditions for the Axis Gates event: Kill 125 Charging Bulls in the Wild West.
Dungeon events
Conditions for the Irregular Crystal event: Has a chance of spawning upon killing any Intermediate difficulty dungeon boss (dropped from mountains enemies).