Act 1: Merveil, the Twisted. It is the final boss of Act 1, located in the Cavern of Anger. Defeating her is the objective of the quest The Siren's Cadence.
Act 2: Vaal Oversoul. Vaal Oversoul is the final boss of Act 2, located on the top floor of the Ancient Pyramid. One must use The Apex, or the complete amulet from the quest Deal with the Bandits in the Dark Altar in order to summon it. Defeating it opens the way to Act 3's City of Sarn.
Act 3: Dominus, Ascendant. It is the final boss of Act 3, located in the Upper Sceptre of God, on the Tower Rooftop (after climbing 3 or 4 staircases in the Upper Sceptre of God) Upon defeating him, Lady Dialla appears to congratulate the player and opens the way to Act 4.
Act 4: Malachai, The Nightmare. It is the final boss of Act 4, located in the Harvest's Black Core's final area: The Black Heart. Defeating him allows the player access to Act 5.
Act 5: Kitava, the Insatiable. It is the final boss of Act 5. The battle consists of multiple phases in which players must damage Kitava, then damage Kitava's Heart, and this occurs alternatively till Kitava is defeated.
2. Act Adversaries 2
Complete each of the following encounters.
Act 6: Tsoagoth, The Brine King. It is the final boss of act 6, located in the Brine King's Reef. Defeating him is part of the main quest The Brine King.
Act 7: Arakaali, Spinner of Shadows. It is the final boss of act 7, located in the Temple of Decay Level 2. It is an ancient Vaal goddess according to the quest log and NPC dialogues. It is also worshipped by people of Azmerian descent. Defeating her is part of the quest The Mother of Spiders. The rescue Silk part of the quest, however, is scripted to be fail.
Act 8: Lunaris, Eternal Moon and Solaris, Eternal Sun. Lunaris, Eternal Moon is the final boss of Act 8. It is one of the bosses of the Solaris and Lunaris fight. The other boss is Solaris, Eternal Sun. When both bosses are defeated, they are unlocked as major gods in the pantheon system.
Act 9: The Depraved Trinity. It is the final boss of Act 9, located in The Rotting Core. It's the combined power of the three lieutenants of Malachai : Doedre, Maligaro, and Shavronne. The boss sometimes applies ground effects that inflict Effluents debuffs (red and purple).
Act 10: Kitava, the Insatiable. It is the final boss of Act 10. The battle consists of multiple phases in which players must damage Kitava, then damage Kitava's Heart, and this occurs alternatively till Kitava is defeated.