Poltergeist can become visible and invisible whenever they want.
Poltergeist appears to be a ghostly or spectral figure with a vibrant, eerie design. The character has glowing green, tattered skin or armor, with sharp, angular eyes that give it a menacing look. Its most distinctive feature is its large, purple tongue hanging out, adding to its spooky and mischievous appearance. The ghostly form looks somewhat monstrous.
Poltergeist's abilities are in the character definition.