Bosses

The bosses and villains you can fight, and where to find each one.

Four of them each keep an Infinity Stone: the Red Skull, the Hollow King, Loki and the Mystical Guardian.

Boss	Where	How it fights
Hrafnar, the Hollow King	Asgard	The last ruler of a golden palace, emptied out by the dark. A dark citadel stands once in every 12 by 12 chunks of the Asgard continent. Three phases: a heavy sword and a ground slam; then hellfire volleys and two Corrupted guards under two thirds health; then faster slams under a third. Drops shards, runes, Asgardian steel, a Rune Core and one piece of legendary gear. It keeps the Reality Stone.
Bifrost Guardian	Bifrost ruins in Asgard	A gold-and-rainbow sentinel that wakes when you come close. It throws bolts from the air and marks the ground with rainbow rings that burst a moment later. At half health it calls two Einherjar. Drops Bifrost Energy Shards and a few Rune Fragments.
Loki	Frozen Sanctum	A ruined Jotun shrine in the snow, where Loki has made himself a court. He stays put until you come within about 24 blocks or hurt him. He keeps the Mind Stone.
Mystical Guardian	Ruined Sanctum	An old sorcerer's spirit bound to a Sanctum Altar. It throws bolt volleys, pushes you away, raises a ward that turns projectiles aside, blinks away from melee and calls two spectral wardens at half health. Winning gives you the Cloak of Levitation and a Mirror Shard. It also keeps the Time Stone.
Mirror Wraith	Mirror Dimension	Keeper of the Mirror Dimension trial. It fires violet shard volleys and splits into reflections that shoot too, so hit them to pop them. Below half health it folds space and drags you in. Start the trial by putting a Mirror Shard on the altar.
Dormammu	Called at a Sanctum Altar with a Dark Sigil	Lord of the Dark Dimension, a towering figure of fire. He fires hellfire volleys, makes flame pillars that erupt under you, and releases a dark pulse when you get close. He calls blazes at two thirds and one third health. Every time a player rewinds time near him with Time Reversal, he loses a chunk of health. Drops the Tome of the Vishanti.
Ultron	Ultron Facility	Waits dormant in a 23 by 23 hall on a lit platform until someone walks in.
Electro	Power Station	Stands dormant under the pylon until you come close.
Green Goblin	Oscorp Lab	Waits on his glider on the roof helipad.
Doctor Octopus	Octavius Lab	Waits beside the fusion reactor.
Mysterio	Mysterio Studio	Waits centre stage.
Vulture	Salvage Yard	Perches on top of the crane.
Swamp Thing	Swamp Grove	Lies dormant on the altar in the middle of the grove.
Catwoman	Jewel Vault	Waits in the vault until you come close. From a few blocks away she steals an item from you and runs. A hard hit makes her drop it, and it also comes back if she dies. Below half health she steals faster. Drops the Cat's Eye Diamond, the key ingredient for the Catwoman suit, plus diamonds, gold and string.
Mr. Freeze	Cryo Lab	Waits in the lab in an armoured freezing suit. Halfway down he says his suit is running hot, and he vents coolant when it runs out. Drops the Cryo Core, the key ingredient for the Mr. Freeze suit and the Freeze Gun, plus blue ice, diamonds and iron.
Sinestro	Qward Fortress	Fights with yellow hard-light constructs. He can override a Green Lantern ring in sight, which switches your ring off for ten seconds, and shield himself with his own ring until it flickers. Drops the Yellow Power Ring, plus gold, glowstone dust, diamonds and Steel Ingots.
Thanos	Titan fortress, in Space	The hardest fight in the mod. He sits on a throne in the Titan fortress until you lay an Infinity Gauntlet on the arm of the throne. He has 1200 health, plus 300 for every extra player, and fights in six phases. He makes illusions of himself, and halves the health of whoever he snaps. He drops the Infinity Gauntlet.
Red Skull	Hydra lair	Sleeps on his dais in the throne room until someone comes close. He keeps the Space Stone.
M'Baku	Warrior Falls, in Wakanda	Leader of the Jabari. He comes down from the mountains when you use a Heart-Shaped Herb on the Challenge Stone, and only one challenge can run at a time. He slams the ground with his club, charges in straight lines, and at half health he roars and shrugs off damage for a while. Beating him drops the Jabari Club and earns the respect of the Jabari: the white gorillas stop fighting you, and a melon slice or an apple tames one.