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Bosses

Path of Exile 2 features a brand new campaign with six acts, 100 distinct environments, 600 monsters and 100 bosses.

Every zone will include a boss. There are 100 bosses. If you die while fighting a boss, you restart the zone and must progress through the zone to fight the boss again, from full health.
All crowd control mechanics (e.g. Freeze/Stun/Immobilise) build up over time, like "poise" allowing them to work on bosses if not immediately applied. Enemies and players also gain resistance to crowd control for a duration after being cc'd, reducing chain stun/freeze. Electrocute lets Lightning damage CC. Stun duration varies by monster
Reviving in the Acts will return you to the start of the zone, instead of right at the boss, to prevent corpse rushing.
Defeating optional Bosses can grant rewards like permanent stat and Spirit bonuses.
Larger bosses can be more mobile because they have multiple hitboxes, unlike just 1 in POE 1
Checkpoints before bosses. Teleports are destroyed in boss arenas. Logging out returns you to the save state you logged out from - no more logout macros. Dying resets the zone.
There will be no death experience penalty in the poe2 champion, but if you die on the road, you will only restart from the entrance and all monsters and zone map will be reset. If you die on the boss, he will have full health.