Encounters

Learn the ins and outs of Undertale's encounter system, including Fight, Act, Item, and Mercy options, and how to navigate monster attacks with different SOUL colors.

Being a roleplaying game, Undertale uses an encounter system in which the battle takes place in a separate system than the game's overworld. You'll enter an encounter (also called a Fight or Battle) when an exclamation mark (!) appears over your character's head.

Encounters are turn based, and you almost always go first. In almost all encounters, you are presented with 4 options at the bottom of the screen: Fight, Act, Item, and Mercy. The way you choose to "fight" your opponents will affect the way the game's story develops. Here is what each option does:

• Fight: After you select fight, you select which monster you want to attack. The game then presents a gradient of sorts and a moving vertical bar. When you hit the confirm button, Z by default, the bar stops, and you inflict damage on the monster based on how close you landed the bar to the center of the gradient. Damage also depends on the weapon you have equipped as well as the monster's defense.
• Act: This is the more peaceful route to escaping encounters. The act menu will offer you a handful of interactive options to try and use on the opposing monster. If you choose the right actions, you can "spare" the monster (See the Mercy bullet below). The menu almost always has a "Check" option which will give you the monster's stats and sometimes a tip to sparing the monster. All other actions will interact with the monster, sometimes resulting in, for example, you earning their trust, lowering their stats, or irritating them.
• Item: As the name implies, this menu let's you use an item in battle. You typically can only use healing items in battle, i.e. items that restore your HP. Some items can cause special effects in particular encounters. You can carry up to 10 at a time. See the Items section of this FAQ for a full listing of items and their effects.
• Mercy: The Mercy menu is necessary for those pursuing a peaceful and friendly journey. This menu offers only two possible options: Spare and Flee. Sparing is the primary way for you to "win" an encounter without killing the monster. You can spare a monster when their name is yellow instead of white (unless you made the sparing color pink or removed it as you can in the tutorial). Some monsters cannot be spared, and you have to come up with more creative ways to win without killing them. Flee basically just let's you run away without engaging the monsters at all. You get no EXP or gold for fleeing.

Your turn ends after you attack, use an Act option, use an item, or attempt to spare when the enemy's name isn't yellow. It is then the monster's turn. During the monster's turn, the monster will first respond to any Act command you used, and then it will, in most cases, launch an attack at you. During their turn, your heart, called your SOUL, will appear in the middle of what's called the Battle Box. You can move your soul anywhere in the battle box to avoid the enemy's attack. The type of attack the monster uses depends on who they are, and there are attacks that come in different colors. These colors have important meanings:

• White: These are default attacks that are harmful to touch. Touching any white attack in any way will cause you to lose HP.
• Blue: To avoid blue attacks, you have to keep your soul still while the attack passes through. You will take damage if you are moving when the blue attack touches you, but they will not hurt you if you are standing still.
• Green: Green attacks restore your HP. These are useful, and you should actively attempt to touch green attacks. Remember, green is good!
• Orange: You should pass through orange attacks by moving into them. They will not hurt you if you're moving. They're the opposite of blue attacks.

In certain boss battles, your soul will change color from red to blue, green, purple, and yellow, with each color having a particular effect. See the walkthrough for dealing with these bosses.

An encounter will end in one of four ways:

• You kill the monster(s): If the monster runs out of HP, they will die, and you will receive both EXP and gold as a result.
• You spare the monster(s) or they spare you: In this case, you will receive only gold after the battle, no EXP.
• You flee: You receive nothing for this.
• You die: If you run out of HP, it's game over!