In March, the ridiculously stacked Psycho Las Vegas revealed what they said was the full lineup, but now one more headliner has been added: Mastodon.

Mastodon join King Diamond (playing Abigail), The Brian Jonestown Massacre, Gojira, Neurosis, Swans, Carcass, Murder City Devils, Sleep, Ace Frehley, Corrosion of Conformity, Chelsea Wolfe, Melvins, Slo Burn, Diamond Head, Manilla Road, Magma, Cirith Ungol, Abbath, Windhand, Pelican, Weedeater, Myrkur, Inter Arma, Khemmis, and more. Seriously, holy shit.

Tickets for Psycho Vegas are still available. Full lineup below.

Earlier this year, Mastodon released their new album Emperor of Sand. They're also touring with Eagles of Death Metal and Russian Circles, including NYC's Hammerstein Ballroom on May 11 (tickets).

Psycho Las Vegas -- 2017 Lineup
Abbath
Ace Frehley
Black Anvil
Blood Ceremony
The Brian Jonestown Massacre
Buzzov*en
Carcass
Celeste
Chelsea Wolfe
Cirith Ungol
Cloud Catcher
Code Orange
Conan
Corrosion Of Conformity
Cough
Cult Leader
Cult Of Luna With Julie Christmas
Diamond Head
Domkraft
Earthless
Elephant Tree (Aka Flights)
Eternal Tapestry
Fister
Floorian
Gatecreeper
GEQ
Gojira
Gost
Graf Orlock
Heavy Temple
Hollow Leg
Inter Arma
Khemmis
King Diamond
Laura Pleasants & Special Guests
Magma
Manilla Road
Merlin
Mastodon
Minsk
Morne
Mothership
Mouth Of The Architect
Mulatu Astatke
Murder City Devils
Mustard Gas & Roses
Myrkur
Neurosis
North
Oathbreaker
Pelican
Pentagram
Psychic TV
The Rods
Ruby The Hatchet
Sasquatch
Saturndust (AKA Flights)
Sleep
Slo Burn
Slomatics
Snail
Sons Of Otis
Sumac
Summoner
Swans
The Skull
Toke
Urchin
Usnea
Vhol
Weedeater
Windhand
Wizard Rifle
Wolves In The Throne Room
Yawning Man
Year Of The Cobra
Youngblood Supercult
Zeal & Ardor