Hands are one of Gaster's primary weapons. Gaster developed his own fighting style, causing him to summon up to seven hands under his control, each one with a different power/ability. With DUALITY, Gaster can summon two giant ones, and with Polychromatism, he can summon both the giant and small ones.
- DUALITY: The hands are all turned into two bigger ones, with the power being amplified way higher than it was before.
- Monotone: All the hands turn of a certain color, amplifying the power of his next attack by 7. As of Season 2, Gaster can only use six hands, therefore his attacks are multiplied by 6.
- Red Attack: Shoots a blast of energy, twice as powerful than normal Gaster Blasters.
- Green Attack: Gaster's hand can spawn a forcefield or a shield to protect someone, however, it drains his energy the longer he uses it.
- Orange attack: This specific hand has the ability to spawn white dots around their target. When the dots turns to orange, they create a deadly explosion.
- Blue Attack: Gaster's hands have the ability to spawn up to 2 blue razor blades in a disc that follows its target.
- Yellow Attack: Gaster has the ability to turn one of his hands (or both when using Duality) yellow that shoots projectiles at a really fast pace.
- Purple Attack: This ability is able to copy anything in front of this hand (the purple one in this case) and is able to copy it’s exact power as well, but it is likely to get destroyed if it is overwhelmed with too many powers.
- Light Blue Attack: This hand has the ability to shoot up to 4 that stick to its objective until Gaster decides to let go or the string is cut off.
- Gaster has holes in his hands which he uses for controlling and using his powers.
- Since Gaster has extremely unique powers, the holes in his hands get filled according to the power he’s using, so he can actually shoot powers from those holes and also shows what he’s using. He was naturally born with it.
- His perseverance power is blocked and he was only able to use it in Yet Darker due to the ”weird void powers”, making them technically not count. It's noted because this hand is blocked and Gaster's max hands spawn is 6.
- Every power that Gaster uses represents each one of the human soul traits' powers.
- Hands' colors and attacks can be the same if Gaster wishes so.
- Hands can be used for other purposes such as melee attacks.