-"Bad Time Trio"-

Chara is a half-monster, half-human.
Sans is a skeleton, a monster
papyrus - skeleton, monster

Sans's magic in Undertale is a combination of supernatural abilities that rely on his knowledge of timelines and the manipulation of spacetime. Below are the key elements of his magical power.
Teleportation and shortcuts
Sans is able to instantly move between points using "shortcuts" - likely a form of spatial teleportation.
Can be in different places in the same room at the same time (for example, in the area near the mysterious door in Snowdin).
His sudden appearances without any signs of approaching (as mentioned by Doggo) confirm this ability.
Telekinesis
When using telekinesis, Sans's left eye lights up, flashing blue and yellow (symbols of patience and justice), while his right pupil disappears.
Allows him to control objects and attacks from a distance.
Gaster Blaster
A primary ranged weapon. It resembles the skull of a dog- or dragon-like creature that fires laser beams.
When fired, the lower jaw splits into two parts.
Comes in different sizes and modes (including a "blue" mode that changes the attack mechanics).
The title refers to V.D. Gaster, hinting at a connection with ancient magic or technology.
Knowing timelines
Sans is aware of multiple timelines and resets (which Flowey notes).
Able to recognize when the protagonist is behaving unusually (for example, repeating actions already experienced in other lines).
On the Genocide Route, he determines how many times the protagonist has killed him based on his facial expression.
Evasion and Endurance
In combat, Sans constantly dodges attacks, which makes him unique among enemies.
His combat magic is extremely energy-consuming: by the end of the battle, he shows signs of fatigue and even falls asleep right in the middle of the battle.
Manipulation of perception and "judgment"
During the "trial," Sans demonstrates the ability to evaluate the protagonist's moral choices (EXP and LOVE), revealing the true meaning of these metrics.
Uses knowledge of the player's actions for psychological pressure (jokes, memory of discards, guilt)

Sans's appearance
Sans is a short, broad-boned skeleton. His typical outfit:

an unbuttoned blue sweatshirt (or jacket) with a hood;

a white sweatshirt or t-shirt under a hoodie;

black shorts;

pink house slippers (according to the Steam trading card).

Characteristic facial features:

a constant wide grin (almost does not change facial expression);

white pupils (disappear when Sans becomes serious);

The left eye has a bright blue iris that flashes yellow and blue during combat.

Sans's character
Sans is known for his laid-back and relaxed demeanor. His key personality traits include:

A love of rest. Often sleeps during breaks at work, exhibiting laziness—even in combat.

Sense of humor. He's known for his jokes and pranks (like shaking hands with a whoopee cushion), which often irritate his brother Papyrus.

Friendliness. Generally kind and friendly, he supports the protagonist on the Neutral and Pacifist paths.

Attentive and observant. Notices small details—for example, accurately counting how many times he's "killed" a player.

Scrupulous. Thanks to her knowledge of timelines, she notices the protagonist's unusual behavior.

Contradictory. Despite his apparent carefree nature, he can be serious and even threatening (especially on the Genocide Path).

Loyalty. Cares deeply for her brother Papyrus and tries to support him.

Dislike of promises. He admits that he doesn't like making promises, as he once broke one (failing to protect fallen people, as Toriel promised).

Empathy. At key moments in the story, he or she shows understanding and evaluates the player's moral choices.

Swap!Papyrus is a version of Papyrus from the alternate Undertale universe (commonly referred to as "Swap"), where the roles of the brothers Sans and Papyrus are reversed: Papyrus is a fearsome, calculating guardian, while Sans is a playful, frivolous prankster. Swap!Papyrus's magic reflects this "inverted" image: it is dark, powerful, and focused on controlling and suppressing opponents.

Key features of magic
Bones with spikes
Instead of Papyrus's classic smooth bones, Swap-Papyrus creates sharp, jagged, and spiked bones. They:

move in sharp jerks;

can pierce or hook the target;

sometimes explode into small fragments upon impact.

Dark aura and shadows
Swap-Papyrus is constantly surrounded by dark energy. He uses it to:

camouflage (dissolves in shadows);

sudden attacks from the darkness;

creating "shadow traps" that restrict movement.

Gravitational manipulation
Swap-Papyrus can distort gravity in the combat zone:

lifts the opponent into the air, depriving him of support;

Throws down sharply, increasing fall damage;

Creates zones of increased gravity that slow down the enemy.

Psychological pressure
His magic is often accompanied by:

illusions (for example, multiple copies of oneself);

sounds (whispers, grinding of bones);

visual effects (flickering eyes, blood-red reflections).

Signature Move: "Corona Spike"
A powerful attack where:

a giant bone column with spikes emerges from the ground;

the target is thrown up and then falls onto sharp ledges;

accompanied by a flash of dark energy.

Defense: Bone Shield
Swap-Papyrus forms a barrier of intertwined, spiked bones. Shield:

absorbs some of the damage;

reflects weak attacks back at the enemy;

can suddenly open like a trap, trapping the enemy.

Energy bursts
In his rage, he releases waves of dark energy that:

stun the enemy;

temporarily disable magical abilities;

leave "marks" on the target, enhancing subsequent attacks.

Features of application
Fighting Style: Swap-Papyrus acts cold-bloodedly, calculating his moves.

Swap Papyrus's appearance
Swap Papyrus is a character from an alternate Undertale universe where the roles of the main protagonists and antagonists are reversed (swap means "exchange"). In this version, Papyrus takes on the role typically reserved for Sans: he is a serious, disciplined guardian, while Sans, in contrast, becomes a frivolous jokester.

Main features of the appearance
Skeletal nature
Like the canonical Papyrus, Swap Papyrus is a skeleton. His skull has prominent eye sockets and a narrow lower jaw, but unlike the original, his facial expressions are more restrained: he smiles less frequently, and his expression is often neutral or stern.

Eyes

In a calm state, the pupils are dark, almost black, without glow.

When using magic or in combat, the pupils glow a bright blue (as opposed to Sans's orange in canon).

His gaze is direct, focused, and rarely "wavering," emphasizing his seriousness. Clothing: An orange hoodie (often with "indirect text messages" on it—details often found in AU fan art), dark green (or "swamp") shorts, and orange and white sneakers. Face and Eyes: He has a small, toothy grin. His eyes are small, their sockets often half-closed, and there are noticeable bags under them. Normally, his eyes are black, but during combat, a bright orange iris appears in his right eye, flashing yellow and orange. Habits: He smokes—the cigarette floats in his mouth thanks to telekinesis (his mouth is usually closed).

Basic types of magic
Technological magic (weapon manipulation)

creates knives and daggers of various sizes - from miniature to gigantic;

can release them in large quantities, saving magical power;

able to combine and modify weapons.

Gaster Blasters

Summons flying dragon skulls that shoot red laser beams;

uses enhanced versions of:

Gaster Star Blasters - A combo attack that absorbs stars;

Blue and orange Gaster Blasters - ram the enemy with the tips of the corresponding color.

Chaos Accelerator

creates energy blasters that shoot powerful beams (including blue ones, with a special effect);

can summon multiple such devices at once.

Astronomical magic

Star Wave - fires star-like projectiles (3-5 each);

Big Wave of Stars - Exploding stars under the enemy;

Moon - attack with rain on the left side of the field;

The sun emits "bullets" clockwise.

Spear Magic

creates multiple magical copies in the air and launches them with the power of thought;

Uses yellow spears that change direction at the end of their path (attack from behind).

Trident Magic

Allows you to create and control a trident.

Blood magic

manipulates his own blood for various actions;

cannot use the blood of other creatures without physical contact or prior extraction.

Animal magic

Butterflies - circle around the enemy, dealing damage on contact (various options: ring, lines, groups);

Worms - created from spheres, move diagonally;

Flies fly to the enemy's soul.

Other abilities

Notes - attacks with musical notes, increasing speed and intensity with each "hum";

Muscular attacks - giant arms flex and extend across the field;

Drops of sweat - a "rain" of drops of sweat falls.

Features of application
Chara uses magic primarily for:

Snowdin's defenses;

protection of monsters and foster family;

Chara from the Storyshift universe is a supporting character in the story, taking over Sans's role. She is the last person to fall into the Underground before the main character, and is accepted by Asgore and Toriel. Chara wears a light green hoodie with an open zipper, a white T-shirt, black pants, red gloves, and boots. She has light brown hair, brown eyes, and pink, flushed cheeks. Her cheeks have permanent pink circles, like blush stickers. Her skin is pale lavender, though the lavender undertone is barely visible. Her eyes have crimson irises with black sclerae. Personality
Chara cares for the monsters in the Underground, especially her family, whom she considers the coolest. She enjoys teasing Frisk (Chara calls them "pretty mirror" due to their physical resemblance) and Asriel (she calls him Rei). Despite their banter, Chara can be easily offended, such as when Frisk says Asriel is cooler than her. In the genocidal storyline of Storyshift, Chara develops a hatred for Frisk after they kill all the monsters, including her family (Asriel, Asgore, and Toriel). In the finale, she engages in battle in the Final Corridor, using the power of her Determination to confront Frisk.