Spell
Spells (JP: まほう) are a mechanic in Deltarune which certain party members can use while in a Dark World. Excluding overworld cutscenes, spells require TP, and can be cast from the MAGIC button during enemy encounters.
Spells have a variety of effects, including harming enemies, healing allies, and pacifying enemies. The power of offensive and healing spells mostly depends on the user's Magic stat, and sometimes the Attack stat as well. A party member's equipment may also influence spells by decreasing TP.
Certain bosses can also cause unique Spells to appear in Kris's ACT menu, and uses both Kris and the spell user's turn when selected. It causes Kris's SOUL to shine its power on the user for an enhanced Spell. Certain Actions may also appear in an ally's Spell Menu, which can have an effect or require TP.
When joining the party briefly, Flowery is listed with several Spells that cannot be viewed in the menu nor used in battle, and are purely cosmetic.

Susie starts with only a damaging spell, and gains support spells over the course of the game.
Rude Buster
Rude damage
Costs 50% TP (40% with the Devilsknife). Deals moderate damage to one foe, depending on Attack and Magic. It deals increased damage by pressing [CONFIRM] right before the projectile hits an enemy.
Healing
[Battle text varies]

Ralsei's spells are centered around supporting the party via healing or helping SPARE enemies.
Heal Prayer
Heal ally
Costs 32% TP. It heals one party member a significant amount, depending on Magic.
Pacify
Spare TIRED foe
Costs 16% TP (0% with the BlueShoes). SPAREs one TIRED enemy.
ReviveSong
Revive ally
Costs 84% TP. Revives an ally to partially full HP. Or heals a large amount if they are not DOWNed. It is always available starting in Chapter 5.

Noelle's spells are ice-themed and a mix of attack and support spells.
Heal Prayer
Heal ally
Costs 32% TP. It heals one party member a significant amount, depending on Magic. It is identical to Ralsei's Heal Prayer spell.
Sleep Mist
Spare TIRED foes
Costs 32% TP. SPAREs all TIRED enemies.
IceShock
Damage w/ ICE
Costs 16% TP (8% with the ThornRing). Deals moderately high damage to one enemy. Upon defeat, the spell freezes the enemy in place. To initiate and progress the Weird Route, each enemy in Cyber City must be defeated using this spell.
SnowGrave
Fatal
Costs 200% TP (100% with the ThornRing). It is only available against Berdly on the Weird Route. Due to its high TP cost, it can only be used with the ThornRing equipped. It deals extremely high damage to all enemies. If used against Berdly, it encases him in a block of ice. This is necessary to continue the Weird Route.
These are ACTs that function similar to spells in that they appear in multiple separate encounters, but are not internally treated as spells.
Check
Useless analysis
Costs 0% TP. It is available in almost every battle, and, with few exceptions, provides only cosmetic information about the enemy.

Susie's Idea
RedBuster
Red Damage

DualHeal
Heals everyone/Heal party
Heals the entire party a significant amount. Against King and Queen, it costs 50% TP and requires Kris and Ralsei to cast. Against the Titan Spawn and Titan, it costs 16% TP, requires Kris, Susie, and Ralsei to cast, and weakens with every use.
These are spells that exist within the game's code, but cannot be used in battle.[1]
[No name]
None[note 1]
Costs -0.4% TP. It is an error handler spell that is used whenever the user does not have a spell, or when they have an invalid spell. Due to its negative TP cost, using it restores 1% TP, and repeats the last line of dialogue. If an ACT or item is not used before using None, or two ACTs are used, the game freezes. It has no flavor text or name in the spell menu or the POWER menu.
Rude Sword
Rude Damage
Costs 50% TP. Deals moderately high damage to one enemy, depending on Attack.
Red Buster (unused)
Red damage
Dual Heal (unused)
Heal All 30 HP
Costs 0% TP. It is an unused spell version of DualHeal. Despite its description implying it heals +30 HP to each party member, it functions identically to the Chapter 1 and 2 version of DualHeal, though it can be used directly by Ralsei rather than through Kris.
ACT
Use action
Costs 0% TP. This is used when viewing Kris's spells through the POWER button in the menu.[2] Using it freezes the game.
- ↑ The spell itself has no name, "None" is the spell's description.
- ↑ gml_globalscript_scr_spellinfo script, Chapter 1
- ↑ gml_object_obj_darkcontroller_draw_0 script, lines 413–414, Chapter 1