All Core Keeper Bosses: Main Story, Optional Bosses and Titans

The main line is a chain of gates. The first three bosses carry the relics that power the Core, the next three are the Titans guarding the outer ring biomes, three dragon Titans form the late-game tier, and the Core Commander closes the chain. Every boss in this section has to fall for the story to advance, and the order below follows the route the game builds for you.

One rule applies to every name in this section, and to the optional and post-game buckets after it: boss health scales with the number of players in the world, with each additional player adding less than the one before, and the exact scaling differs from boss to boss. A solo player and a full crew of eight are therefore reading the same roster at different weights, which is worth remembering before you judge any single fight as easy or unfair.

Glurch the Abominous Mass is the giant slime waiting in a clearing in the Undergrounds, close enough to the Core that its thumping is an early-game rite of passage. Ghorm the Devourer never waits anywhere: the huge grub circles the Core on a wide ring track, ploughing through the Clay Caves and the Forgotten Ruins, and you intercept it as it passes. Malugaz the Corrupted holds a throne room in the Forgotten Ruins, summoned with the Skull of the Corrupted Shaman assembled from crystal skull shards. Each of the three drops one relic for one of the Core's statues, and the third relic, Malugaz's Stolen Crystal Heart, completes the set: the Core powers up and the sealed outer world opens. A dedicated guide covers these three fights in full; here they matter as the lock on the whole outer map.

Past the Great Wall, the route runs through three Titan biomes in material order. Azeos the Sky Titan rules Azeos' Wilderness and is summoned in its arena with a Large Shiny Glimmering Object. Omoroth the Sea Titan turns the Sunken Sea into an arena of open water, where the fight is a naval one. Ra-Akar the Sand Titan waits in the Desert of Beginnings, and clearing it completes the ring of three. Together the ring Titans are the middle of the main story: three biomes, three gear tiers, three very different arenas.

After the ring come Druidra the Wild Titan, Crydra the Ice Titan and Pyrdra the Fire Titan, a trio of dragon Titans who form the late-game Titan tier. The sources name them as a group alongside the ring three (the six together are the game's Titan souls), and they are best planned as one tier of preparation: finish the ring, climb the last material tiers, then work through the dragons as the road bends toward the finale. Treat any guide that insists on a strict internal order among the three with care; the roster itself presents them as a set.

The Core Commander is the tenth main boss and the current final boss of the main story. Everything on the route funnels into this fight: three relics, three ring Titans, three dragons. Beating the Commander completes the main chain, and it also changes what the roster means from that point on, because the three bosses in Section 3 are defined by standing after this one.

Optional bosses ask nothing of the story. Each one belongs to a biome and an era of your gear, and the natural time to fight one is the time you are already living in its home ground. There are 7 of them, and the roster below is the whole set. Notice the family pattern running through the list: alongside the early Hive Mother, the crossover King Slime and the sea-going Atlantean Worm sit three giant Masses, one tuned to each of the outer biomes, so the optional bucket doubles as a set of rematches that grow with the map.

One line per boss is enough to place each of them:

One sentence of version history explains the Hive Mother's odd reputation: before 1.0 she occupied a statue boss slot at the Core, and her statue was replaced by Malugaz's in version 1.0.0.1, which is why older guides still file her as a required boss.

Three further bosses stand beyond the main story. All three are classified as post-game bosses, all three arrived in major updates after the 1.0 launch, and none of them is a gate on the main route: the Core Commander comes first, and these are what a finished world still has to offer. Geographically the bucket splits into two trips: one back south into the Desert of Beginnings for Nimruza, and one long push north into Breaker's Reach, where the other two share a single biome and can be planned as one expedition.

Nimruza, Queen of the Burrowed Sands waits in a dungeon inside the Oasis, a sub-biome of the Desert of Beginnings, and she is summoned by placing Corrupted Sap on her rune circle. She arrived with update 1.1 and is the most approachable of the three post-game fights: a return trip into a biome you already know, fought with endgame gear. Her guaranteed named drop in the wiki's table is the Brood Void Neuron, one of the Void Neuron items carried by this post-game tier.

S.A.H.A.B.A.R. is a giant mechanical boss in Breaker's Reach, the northernmost biome beyond the Passage, and it is activated by placing a Profane Override on its summoning circle. It arrived with update 1.2, alongside its home biome, and it shares that biome with Oblidra below, so one expedition north can be planned around both fights. Its named drops include the Herald Void Neuron, the counterpart to Nimruza's Brood piece.

Oblidra the Void Lord is a Hydra-type boss that wanders Breaker's Reach with no fixed arena, summoned near its position by placing the Wind Organ of Void. The wiki describes it directly as a post-Core Commander boss, and it arrived with update 1.2 together with S.A.H.A.B.A.R. and the biome they share. Oblidra belongs to the Wind Organ Hydra family, while the six Titan souls remain the ring three and the dragon three from Section 1.

The last bucket holds 2 names: Haunted Hive Mother and Awakened Azeos. Per Fandom's listing, these are seasonal event variants of two bosses already on this roster, alternate forms tied to seasonal events rather than permanent stops on the map. They are listed here so the roster is complete, and they stay outside the arithmetic above: variants of existing bosses, filed separately from the 20 named bosses in the main, optional and post-game buckets. If a name from this bucket shows up in seasonal coverage or an event announcement, file it mentally as a limited-time form of a boss you already know, and the roster stays easy to read all year round.

Use 18+ named bosses as the safe total. The roster itself breaks down as 10 main story bosses, 7 optional bosses and 3 post-game bosses, which names 20 in total, and the 2 seasonal event variants sit outside that count. The 18+ wording stays in place because it is the total the sources support without argument, while the buckets show you exactly where every name sits.

The Core Commander is the final boss of the main story, the tenth name on the main route. The story does not end the roster, though: Nimruza, S.A.H.A.B.A.R. and Oblidra are post-game bosses who come after the Commander, so a finished main story still leaves three named fights on the list.

Treat the event variants as seasonal. Haunted Hive Mother and Awakened Azeos are listed as seasonal event forms, so plan around them while their event is the current one and expect the permanent roster to be the everyday reality: the base forms of the Hive Mother and Azeos stay in the world as regular optional and main story bosses, and the variants are the limited-time layer on top.