the canonical Genocide Route, Sans is the final boss. He is a relaxed, humorous skeleton who fights you out of desperation to prevent the timeline from being erased. [1, 2, 3, 4, 5]

• What he is wearing: An unzipped blue hoodie, a white t-shirt, black shorts with white stripes, and pink-white slippers.

• His head & smile: He has a round skull with black eye sockets and tiny white pupils (which disappear when he is serious). He constantly wears a wide, unchanging, toothy grin.

• His favorite thing to do: Telling terrible puns and jokes, sleeping on the job, and eating at Grillby’s. [1, 3, 4]

Undertale Last Breath (Hard Mode)

Undertale: Last Breath is a popular fan-creation (AU) where Sans receives intense training from W.D. Gaster to stop the human. [, 2, 3]

Abilities & Fighting Style:

• New Abilities: Along with his original moves, he gains advanced bone manipulation (orange and blue attacks), Gaster Blaster lasers, soul modification, bone-zones, and the ability to teleport the player. [, 2, 3]

• Spam vs. Strategy: In the hard mode phases (such as Phase 3 and beyond), Sans attacks very aggressively and rapidly. He does not just spam moves blindly; rather, he relentlessly overwhelms the player with dense, screen-filling barrages and complex projectile ricochets designed to break standard battle rules. He uses a blend of slow, highly technical hazards and fast, spammy projectiles. [1, 2, 3]

• Overall Mechanics: His attacks are highly technical, requiring active, rapid-fire dodging (such as navigating spinning bones, ricocheting lasers, and walls) rather than simple twitch reactions. He manipulates game mechanics and moves constantl sans is also one hp but sans can dodge very well but he has stamina he gets tired and sweaty in long fights but he doesn’t act sweaty but tired.

Last Breath Sans Phase 2 is a desperate, berserk state triggered after he runs out of dodges and takes a fatal slash. Expecting to die, he realizes his timeline memories and an intervention from W.D. Gaster have kept him alive at 0.0001 HP, granting him one last stand to defeat the human. [1, 2, 3, 4]

Here is how his combat and stamina work during this stage of the fight:

• Ability Spammability: He is significantly more aggressive than original Undertale Sans. He spams a barrage of complex, multi-colored projectiles, unleashes rapid waves of Gaster Blasters, and manipulates gravity and the physical bounds of the screen itself. Rather than typical dodges, he uses a bone in his hand to actively block your attacks. [1, 2, 3, 4, 5]

• Stamina & Exhaustion: Sans exhausts himself rapidly due to his wounds and overwhelming magical output. He begins sweating and heavily showing the effects of fatigue as the relentless bullet-hell patterns of his second phase progress, bringing the battle closer to its climax

Last Breath Sans Phase 3 is the climax of a popular Undertale AU (Alternate Universe) fangame. Pushed to the brink of death, Sans is possessed by the spirit of W.D. Gaster. He becomes a relentless, crazed puppet throwing his absolute strongest, un-dodgeable final attacks. [1, 2, 3, 4]

Here are the specific details regarding his form, abilities, and mechanics:

Appearance & Lore

• What happened: Sans survives Frisk's fatal slashes at death's door. With no dodges left and waiting to die, he makes a deal with "the Him" (W.D. Gaster) who takes over his body to finish the fight. [1, 2]

• What's on his head: He has a jagged fracture on the right side of his skull extending to his eye, and another shorter crack going from his left eye to his jaw. [1, 2]

• What's on his eyes: The shade between his eyes is pitch black, making them look connected. His eyes flash rapidly with a static-like fuzz, switching between black and white. His right eye is slanted downward with the eyelid halfway closed. [1, 2, 3]

Expressions & Personality

• Expressions: He has an unnaturally wide, crazed smile. His expressions constantly shift to mirror W.D. Gaster's. Sometimes, his teeth disappear entirely, revealing a hollow, toothless grin.

• Who is controlling him: W.D. Gaster is controlling his mind and body, directing him like a marionette.[1, 2, 3, 4]

Abilities & Combat Style

• Abilities: He uses his classic Bone Manipulation, Blue Bones, Karma damage, and Gaster Blasters. Uniquely, he can also use Orange Bones (which require the player to move through them to avoid damage), shift screen gravity, and even alter the menu buttons. [, 2, 4]

• Spam vs. Skill: Gaster unleashes everything in a masterful barrage of overlapping, multi-directional attacks. The phase is often characterized as a complex, bullet-hell survival segment where the player must endure his relentless spam of blasters and bone-zones. [1, 2, 3]

• HP: While standard Sans has only 1 HP, Phase 3 is a survival phase where he cannot be killed initially. He has functionally infinite HP until the story's timer or fight sequences are triggered to end the battle.[1, 2, 3, 4, 5]

Stamina & Flight

• Stamina: Rather than getting tired in the traditional sense, he eventually runs out of magical energy as his body fails and breaks down completely under Gaster's control. [1]

• Flight: He does not have the ability to fly; however, he heavily utilizes teleportation, levitation-style telekinesis, and screen-flipping mechanics to disorient his opponent

W. D. Gaster is the brilliant but tragic former Royal Scientist of the Underground in Undertale, who preceded Alphys. He is notoriously known as the creator of the CORE, the subterranean power source. [1, 2]

Because he is a deeply hidden and unconfirmed entity in the game, a lot of what surrounds him is rooted in community speculation. Here is how the details break down: [1]

What He Is Wearing

• Canon: Gaster's actual canonical outfit is unconfirmed.

• Fanon/Theory: He is most commonly depicted by the community and fan animations wearing a long, sweeping black or dark gray robe or an elegant black overcoat over a white undershirt. [1, 2, 3, 4, 5]

Head and Face Appearance

• The "Mystery Man" Sprite: The community generally associates Gaster with an NPC in the game internally named "Mystery Man".

• Face: His face on this sprite is typically a stark white, smooth oval with dark, hollow eyes and a permanent, wide smile.

• Cracks/Fissures: He is commonly shown having distinct black cracks or fissures running down from the top of his head to his eyes and stretching across his face. [1, 2, 3, 4, 5]

Abilities

Gaster’s canonical abilities are a mystery, but through fanon (such as popular animations like Glitchtale), he is frequently portrayed with the following powers: [1]

• Gaster Blasters: The ability to summon giant, dragon-like skulls that fire powerful, destructive blasts of magic.

• Chroma Hands: Floating skeletal hands (each representing different soul traits) that can shoot projectiles, create barriers, or tether opponents.

• Space and Time Manipulation: The ability to teleport across realities, a nod to him being "shattered across time and space". [1, 2, 3, 4, 5]

Likely Known As

• The Man Who Speaks in Hands: A prominent alias given to him by NPCs in the game.

• Dr. W. D. Gaster / Wing Ding Gaster: A direct reference to the "Wingdings" font, which he uses to speak.

• The Royal Scientist: His former title in the Underground