Frightgeists are a Rare psychic element Slug that is coloured in light blue and white. Their protoform has a skeletal pattern. Its major appearance is in the episode "Deadweed" and is found in the cavern of the same name. This slug has mostly fear-related moves. They are a notable Slug in that they are the only known Slug who can directly attack a Darkbane.
- Protoform Abilities - Makes you feel creeped out; can be an early warning system of approaching danger.
- Frightningrod - Hits an opponent creating an overwhelming, uncontrollable fright response.
- Slugbane - Creates the illusion of a monstrous slug predator, scaring an opponent's slugs. Panicked ammo is hard to control.
- Mysteria - Ghost mode can penetrate walls.
- Spellaport - Creates portals in the air that can reroute fired slugs and attacks.
- Ectophasm - Ghostly ectoplasm energy used as slashing arms.
- Ghostshroud - Bits of ectoplasm break off and turn into swirling ecto-beings that act as a shield.
- Arachnoshroud: "Arachnet"+"Frightgeist" - TBD. It hasn't officially debuted in the series yet.
- Club Slug (First appearance)
- Shadows and Light
- Bandoleer of Brothers
- Light as Day
- The Fall of the Eastern Champion (Appears in flashback(s))
- In the episode "Club Slug", Kord is holding a Frightgeist.
- The Frightgeist's Megamorph Protoform is first seen in Slugterra: Slug It Out 2.