Spectrier, Official Website

Spectrier’s Ability, Grim Neigh, is a new Ability introduced with the Pokémon Sword Expansion Pass and Pokémon Shield Expansion Pass. When a Pokémon with this Ability knocks out a target, its Sp. Atk stat is boosted.

Glastrier and Spectrier location in Pokemon Scarlet and Violet

Pokemon Sword and Shield Officially Reveals Glastrier and Spectrier

Nightmare the Spectrier by mojo1985 -- Fur Affinity [dot] net