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Beat Undyne without violence & befriend her as a Pacifist
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The Pacifist and Neutral routes in Undertale can challenge even the most seasoned gamers. But, with some help, you can beat even the trickiest fights, including your confrontation with Undyne! We’ve compiled this comprehensive guide to make your experience battling Undyne go a little more swimmingly (pun intended). Read on, and we’ll show you exactly how to spare Undyne while following either the Neutral or True Pacifist routes—and even befriend her.

Quick Steps

  1. Enter Undyne’s cave to initiate the battle and wait for her to attack.
  2. Block 6 of Undyne’s attacks with your shield while in Green Soul mode.
  3. Choose the Flee option and run away from Undyne in Red Soul mode.
  4. Block another 4 attacks from Undyne when she catches you.
  5. Run away again as soon as Undyne switches to Red Soul mode.
  6. Block a final 8 attacks after Undyne catches you, then run away once more.
  7. Run to Hotland, where Undyne will collapse; give her water to befriend her.
Section 1 of 3:

How to Spare Undyne (Pacifist or Neutral Route)

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  1. Undyne is the third boss in Undertale’s Neutral and True Pacifist routes, waiting atop Waterfall’s crag. When you first approach, she’ll make a speech and tell you to “Step forward when you’re ready.” Afterward, you can head into the cave, and the battle will begin. [1]
    • Undyne also appears in the Genocide route and eventually turns into Undyne the Undying (but this doesn’t happen in Pacifist or Neutral).
  2. At the beginning of the battle, you’ll see a small heart in the white square Undyne is standing on; this represents the battle’s current “Soul mode.” It’ll be red by default, but Undyne will immediately turn it green before attacking. In this mode, you must use the arrow keys to move your shield and block six attacks in total. [2]
    • While in Green Soul mode, you can’t move or attack; thus, you can only block the arrows she throws by aiming your shield in the direction each one comes from.
    • After six attacks, Undyne will turn your soul to the Red Soul mode again.
    • Undyne will use her spear to switch between Red and Green Soul mode.
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  3. 3
    Run until Undyne catches you. Choose the “Flee” option to run away from Undyne— do not attack her . You’ll have a few seconds to run further into the cave! Be aware that Undyne will catch up with you, but that’s part of the process (you’ll have to flee from her multiple times to spare her). [3]
  4. After Undyne catches you, the second phase of the battle will begin. Much like the first, she’ll activate Green Soul mode, and you’ll have to deflect arrows with your shield—but you only need to block her attacks four times before re-entering Red Soul mode. [4]
    • During the battle, pay attention to the arrow colors. White-blue arrows are far away, red arrows are near the soul, and yellow arrows can reverse. So, if a yellow arrow attacks from the top, it will hit you at the bottom.
    • Undyne’s arrows can be swift or very slow in terms of speed. Luckily, blocking them isn’t super hard as long as you stay focused!
  5. 5
    Run until Undyne catches you again, for the last time. Select “flee” as soon as you’re in Red Soul mode. The scene will change and show you in a tunnel; just like before, run down the tunnel until Undyne catches you, and the third phase of the battle begins. [5]
  6. 6
    Deflect more of Undyne’s attacks in the final battle phase. Undyne will switch your soul to Green Soul mode and throw more arrows at you. This time, eight attacks must be blocked before you’ll go back to Red Soul mode and get the chance to flee again. We promise, this is the last round! [6]
  7. Once your heart changes to red and you’re in Red Soul mode, flee for a final time toward Hotland. This time, Undyne will be tired and struggle to catch you. Additionally, if you spare Papyrus , he’ll call you while you’re running on the screen that says, “Welcome to Hotland!” [7]
    • Undyne will not move during this call. After that, keep running until you reach Hotland, and you will have successfully spared Undyne.
  8. 8
    Give Undyne water (or proceed into Hotland). As you reach the checkpoint and bridge, you’ll also see Sans sleeping there. Undyne will pause to look at Sans, then stop chasing you and collapse from overheating in her armor. At this point, you can bring her a cup of water from the nearby water cooler, which will let you befriend Undyne. Otherwise, just keep going into Hotland. [8]
    • If you’re on the True Pacifist route , you must bring Undyne the water so you can befriend her.
    • If you’re on the Neutral route, you can decide to befriend her or leave her there without water.
    • If given water, Undyne will get up and leave (but you’ll see her later on in the game).
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Section 2 of 3:

Undyne’s Attacks & Soul Modes

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  1. It’s important to understand the two different soul modes in the Undyne battle! In the Green Soul mode, your soul can’t move, flee, or attack. Undyne will throw arrows at your soul (the little heart) from all four directions. In this mode, your soul has a shield-like spear, given to you by Undyne, that can be used to block her attacks. [9]
    • This mode only appears during the Undyne battle in Undertale .
  2. 2
    Red Soul mode Red mode is the game’s normal mode, allowing you to behave normally (and move, if you choose). While in Red mode, Undyne launches spear volleys that deal 5 damage per hit; additionally, right after changing the Soul mode to Red, she throws one spear at you that does 4 damage. [10]
    • In the Genocide route, Undyne the Undying uses other attacks, including summoning rings of spears (and individual spears) targeting your soul.
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Section 3 of 3:

Beating Undyne in Battle

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  1. 1
    Neutral route If you choose to defeat and kill Undyne instead of sparing her, simply choose to “Fight” (instead of “Flee”) when it’s your turn on Red Soul mode. When her health bar is completely depleted, she’ll acknowledge your strength and use her Determination to attack some more; however, she’ll get slower and slower until she disintegrates into dust. [11]
    • You can defeat Undyne and maintain your Neutral route (whereas fighting Undyne isn’t an option for a True Pacifist playthrough).
    • Many of Undyne’s Neutral route attacks are telegraphed, making them easier to get accustomed to and dodge or block.
  2. 2
    Genocide route If you’re following the Genocide route, you’ll meet the Monster Kid near the cave where you face Undyne in the Neutral or Pacifist routes. If you “Spare” him, you’ll switch to the Neutral route. If you “Fight” him, you’ll continue the Genocide route; Undyne will intercept the attack meant for him and appear to be mortally wounded. Then she’ll stand up and face you, changing to “Undyne the Undying.” [12]
    • As Undyne the Undying, her attacks are faster and deal more damage (between 8 to 12 per attack).
    • During the Red Soul phase, Undyne throws arrows rapidly. The best way to avoid them is to keep close to the walls as you fight.
    • During the Green Soul phase, Undyne will throw flip arrows—so it may take a moment for you to adjust and start blocking them fast.
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Community Q&A

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  • Question
    What happens if I don't give Undyne the water?
    Bawana 451
    Community Answer
    If you ignore her fainting and walk on, if you go back to her home and talk to Papyrus, he will say she got heatstroke and is resting - and mutter about destroying you. Also, you go from pacifist to neutral.
  • Question
    Will she catch me again, or will she just let me go?
    Community Answer
    Once you enter the Hotlands, Sans will appear at one of his hot dog stands. When you pass him, Undyne will stop to look at him for a moment, giving you more time to run away. After a few seconds, she will notice that you are getting away and continue chasing after you. She will not be able to catch you again due to her pause. Once you cross the bridge, Undyne will start to slow down, and say, "Armor... so... hot..." and she will faint right on the bridge. Conveniently, there is a water dispenser right there, so you will have the option to either give her the water, or to just leave her be. If you choose to give her the water, she will get back up and walk away, saying nothing.
  • Question
    Is there any code to defeat Undyne without killing her?
    Undertale4141
    Top Answerer
    There are no cheat codes in Undertale. Re-read the article or watch the video to get past Undyne without killing her.
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      Tips

      • Keep lots of food, such as Temmie Flakes or Crab Apples, in your Inventory. You might need them during battle.
      • Undyne's attacks are actually pretty easy to memorize; just pay attention to the patterns she uses.
      • The True Pacifist route can be difficult, but stay determined! Your efforts to avoid killing anything will lead to friendship with the Undertale characters—and earn the game’s ultimate True Ending.
      Show More Tips

      Tips from our Readers

      The advice in this section is based on the lived experiences of wikiHow readers like you. If you have a helpful tip you’d like to share on wikiHow, please submit it in the field below.
      • When and if you flee, start running right when you get out of the battle screen, as it will take her a second to realize what has happened.
      • Using the Plead act has a chance of making Undyne's attacks easier to dodge. If you have nothing else to do on that turn, try pleading.
      • When in Green Soul Mode, use the act "Plead." Eventually, this "reminds her of someone," and her attacks will slow down slightly.
      • Get as many healing items as you can, and make sure to not go into her fight with an empty inventory.
      • Need money for heals to get past Undyne? Keep stepping on the pink guy to get infinite gold.
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      Reader Success Stories

      • Anonymous

        Jun 4, 2024

        "I am about to fight Undyne on Pacifist, and I needed help on how to do that. This helped me a bunch!"
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