It's an old mask that tries to lure in and corrupt humans to possess them. His words are alluring and he manipulates his prey to make them put him on. Once done, they corrupt every thought of his host, making them evil and twisted.

evil mask trying to possess a human

He is the leader of the Inkies and INKT Corporation, who wqnts to become the planet's ruler by engulfing it in ink. He is ruthless and a lawful yet evil dictator with a strong dislike for colour or anything that is not his way or image. He wants to rule the planet, indoctrinating people by making them drink ink, which brainwashes them and turn them into an inky. He is very short-tempered, quite bossy towards everyone.

lawful, evil, devious, ruthless

Antasma is antagonist of Mario & Luigi. He seeks power from the Dark Stone and vows to rule the world. Called "King of Bats", Antasma makes for his namesake with a mask that mimics bat ears, long pointy fangs and a cape that mimics a bat's wings. Mostly cloaked, Antasma has sharp claws in his hands and a skeletal body. He makes careful decisions, since after his imprisonment, such as choosing whose power he needs to help realize his dreams.