Abyss

Abyss bosses can be located in the Abyss region found in Parliament Square.

To spawn an Abyss Boss the player must first accept a quest from NPC Titus in Parliament Square, and then close 5 Hellrifts which correspond to their respective Boss.
These rifts can be found in instances around Parliament Square and after 5 rifts of the same element have been closed the quest will alert the player that a Boss has appeared in the Abyss.

"Find the Rifts. Seal the foul tears between world. When the masters come to inspect the damage, kill them without hesitation."
~Titus

Talox

Talox can be spawned by closing 5 Spectral Rifts found in Westminster Catacombs level 1-10 with 25% chance and in level 11-15 with 100% chance .

Monster Type: Spectral

Drops: Retrainers, Skill Tokens, exclusive Dye Kits, mythic quality Abyss weapon, Pets, Talox's Tormented Soulband.

Squadro

Squadro can be spawned by closing 5 Electrical Rifts found in Westminster Catacombs level 1-10 with 25% chance, Middlesex Guildhall, Storey's Gate, Great George Street, Birdcage Walk, St. James Park.

Monster Type: Demon

Drops: unique Abyss Armours, Skill Tokens, Squadro's Cursed Crystal.

Dreadnaught

Dreadnaught can be spawned by closing 5 Physical Rifts found in Westminster Catacombs level 1-10 with 25% chance, East Treasury, West Treasury, Treasury Basement, Westminster Tunnels, Strutton Ground Market.

Monster Type: Beast

Drops: unique Abyss Armours, Skill Tokens, Dreadnaught's Accursed Circle.

The Fulcrum

The Fulcrum can be spawned by closing 5 Fire Rifts found in Westminster Catacombs level 1-10 with 25% chance, Lower Parliament, Upper Parliament, Parliament Sewers, Westminster Bridge, York Road.

Monster Type: Necro

Drops: unique Abyss Armours, Skill Tokens, Fulcrum's Spitefull Scalework.