Question

What bosses appear the next day if not killed? If I'm not wrong one example is the first apparition of Gaz'Haragoth.

Answer 1

Generally speaking, not killing a boss does not affect its chance of spawning again. So if a boss' spawning interval is between 7 and 15 days, not killing it won't make it reappear faster. Bosses which can spawn on 2 or more days in a row are due to other mechanics:

• Gaz'haragoth, like you mentioned, spawns every day on the Roshamuul Mountain as part of the Roshamuul Quest world progress.
• Bosses with multiple spawn locations, such as White Pale or Tyrn, can spawn two days in a row because each day will be a spawn on one of the locations. Each location's interval is independent from the other.
• Bosses that spawn due to Mini World Changes, for example Bank Robbery Bosses. MWCs have a chance to be triggered every day and there's a small chance it will happen two days in a row.
• Bosses that can be forced to spawn due to the Varying Monster Spawn system, for example Crustacea Gigantica (not really a boss but usually deemed so by players) or Burster.
• Event bosses like The Mutated Pumpkin that spawn daily during the event.