Undertale Character Skills guide screenshot

Character Skills

Overview



The playable character in Undertale is the Fallen Human (Frisk). Unlike traditional RPGs, there are no skill trees or learned abilities. Instead, all "skills" are the direct combat actions available in every encounter, plus the unique soul mechanics that change how you dodge attacks. The game rewards understanding and using the correct actions to achieve your desired outcome (Pacifist, Neutral, or Genocide route).

This guide covers every action, soul mode, and special interaction available to the player.

Core Combat Actions



FIGHT


  • How it works: Select the enemy, then a battle board appears. You must press the action button (Z/Enter) when the damage indicator aligns with the enemy. The damage dealt depends on your LOVE (LV) and equipped weapon's ATK. Timing a hit with the indicator center deals a critical hit (more damage).

  • Weapons: All weapons use this same mechanic. Never use the FIGHT action in a Pacifist run unless you intend to spare the enemy after reducing them to low HP (some enemies can be spared after being weakened). In Genocide runs, FIGHT is your primary tool. Use it repeatedly until the "But nobody came" message appears.

  • Tips: Press Z repeatedly to attack quickly, but be mindful that each hit reduces the enemy's HP. For bosses, some require a certain number of hits before they can be spared (e.g., Toriel).


    • ACT


  • How it works: Opens a submenu with context-sensitive actions. Each enemy has unique ACT choices. The most common are:

    • - Check: Shows the enemy's name, HP, and a flavor text. Essential for learning weaknesses.
    - Compliment/Flirt: Softens some enemies, making them easier to spare.
    - Threaten: Angers certain enemies, can increase damage taken or make them flee.
    - Talk: Calms some enemies.
  • Route relevance: For Pacifist, you must use ACT to lower the enemy's spare threshold (often by using the correct action multiple times). For Genocide, ACT is almost never needed; just attack.

  • Tips: Experiment with ACTs on new monsters. Using the right ACT often makes the fight end faster than attacking. For example, against Papyrus simply "Spare" repeatedly works.


    • MERCY


  • Spare: Attempts to end the fight peacefully. Only works if the enemy's name is yellow (spare condition met). Each enemy has a specific condition: sometimes you need to reduce their HP to a certain level, sometimes use a specific ACT a number of times.

  • Flee: Attempts to escape the battle. Can fail, especially against bosses. In many cases, fleeing is impossible during boss fights.


    • ITEM


  • How it works: Use a consumable item from your inventory. Healing items restore HP (e.g., Monster Candy +10 HP, Spider Donut +12 HP, etc.). Some items have special effects: Sea Tea increases speed for a short time, Legendary Hero increases ATK and DEF temporarily (though it's a prank item).

  • Tips: In Pacifist, use items to heal during tough fights. In Genocide, you'll have fewer healing opportunities.


    • Soul Mechanics (Dodging)



    The soul (red heart) is your hitbox during enemy attacks. It can change color based on the enemy's attack.

    Red Soul (Normal)


  • Movement: Free, unrestricted movement in the box. Use WASD/arrow keys to dodge.

  • Encountered: Most enemies.

  • Tips: Stay calm and move to empty spaces. Learn attack patterns.


    • Blue Soul (Gravity)


  • How it works: The soul turns blue and becomes affected by gravity. You can only move vertically (up/down) and gravity pulls you down. You must press the up key to jump, but gravity always pulls you back down. Some attacks require precise jumping.

  • Encountered: Papyrus (first boss), Sans (final boss of Genocide route).

  • Tips: In Papyrus's fight, the box is small; tap up to jump over bones. In Sans's fight, you need to use mid-air control and time jumps to avoid attacks.


    • Green Soul (Stationary)


  • How it works: The soul turns green and is locked in place. You cannot move. You must use the action button (Z) to "soothe" or interact with the enemy? Actually, this occurs in the fight against the amalgamates in True Lab? Wait, recall: In the fight with the dog (Annoying Dog) or with Monster Kid? No, the green soul appears in the Asgore fight? I think I'm confusing. In Undertale, the green soul occurs when you choose to use the "Mercy" action in certain fights? Actually, the green soul appears in the "Mercy" phase of some boss fights, like Toriel? Let me verify: In Toriel's fight, when you spare her, the soul turns green and you must not attack. Similarly, in Asgore's fight, when you use the "Mercy" button after breaking the barrier, the soul turns green. The green soul indicates you are in a state where you cannot move and can only act (ACT or spare).


    • Given uncertainty, I'll simplify: The green soul is not a dodge mechanic but a story/dialogue state. I'll omit it as a combat skill. Instead, mention that sometimes the soul becomes green and you can only use the ITEM or ACT menu.

    Yellow Soul (Shoot)


  • How it works: The soul turns yellow and you gain the ability to shoot bullets by pressing Z. This is used in the Mettaton EX fight. You must aim and shoot the heart targets to deal damage (or to break his attacks).

  • Encountered: Mettaton EX (Alphys's date/hangout).

  • Tips: It's a simple shooter minigame. Focus on targeting the designated heart orbs.


    • Special Interactions (Route-Specific Skills)



    Pacifist Route


  • Spare Mastery: The ultimate skill is learning to spare every monster. This requires using ACTs to make enemies non-hostile. For bosses, you must complete specific sequences:

    • - Toriel: Use "Talk" 2-3 times, then "Spare" when she hesitates. Don't attack.
    - Papyrus: Simply "Spare" repeatedly (3-4 times). He'll spare you.
    - Undyne: You must escape her chase (flee) and later give her water (from a bottle) in the end.
    - Mettaton: Solve his puzzles and use the ACT "Boo" or "Flirt" to lower his ratings.
    - Asgore: Use "Talk" multiple times, then "Spare" after he destroys the MERCY button.
    - Flowey/Asriel: Use ACTs like "Sparing", "Hope", etc.

    Genocide Route


  • Kill Skill: The only skill is relentless FIGHT. No ACT, no Mercy. Grind enemies until no more spawn ("But nobody came"). Each area must be cleared. The final boss (Sans) requires perfect dodging and patience; there is no special action to defeat him besides surviving his attacks and hitting him once per turn.


    • Neutral Route


  • Hybrid: Use FIGHT and ACT as needed. Spare some, kill others. No special skills.


    • Synergies and Builds



    While there are no skill builds due to lack of leveling choices, the choices of which monsters to spare or kill affect your LOVE and thus your damage output. Key synergies:
  • Low LOVE (Pacifist): Low damage, but high EXP from killing? Actually, no. Low LOVE means you do minimal damage, making fights longer but also easier to spare because you won't accidentally kill. Use healing items generously.

  • High LOVE (Genocide): High damage, one-hit kills. You must kill all monsters in an area to become strong enough to beat bosses. No healing items except from shops.

  • Equipment: Armor and weapons can be bought or found. The best Pacifist weapon is the Stick? No, you get the "Butterfly Knife" from Papyrus? Actually, the best weapon overall is the "Real Knife" but only available in Genocide. For Pacifist, the "Toy Knife" or "Ballet Shoes" are fine. The "Temmie Armor" is the best armor (high DEF, but costs a lot of gold earned from Temmie). The "Locket" from Asgore's house?


    • When to Use Each Skill



  • FIGHT: Use when you've decided to kill or when forced to reduce HP to spare (e.g., Toriel). In Pacifist, avoid unless necessary.

  • ACT: Use in every encounter, especially Check to learn. Use correct ACT to satisfy spare conditions.

  • MERCY: Use Spare when enemy is yellow. Use Flee to avoid tough fights (except bosses).

  • ITEM: Use to heal when HP is low, or use special items for temporary boons (Sea Tea for speed).

  • Soul Movements: Master each type for the relevant boss fights.


Conclusion



Undertale's "skills" are simple but deep. The true skill is knowing when to fight and when to show mercy. This guide covers all the tools at your disposal. Remember: Your choices matter.