Idulnas (also known as The Third and The Third Minion of Gozer) is an entity that can travel through reflective surfaces and posses mortals.
Although technically the 'creation' of Ray Stantz, Idulnas came into being as a direct response to Gozer's defeat. Its purpose was to bring about a re-selection, so that Gozer could come in the 'intended' way and complete its task of destruction.
Idulnas appeared in various reflective surfaces across New York City some time after the "Infestation" Incident, however his first host would be through a man named Jim Silver.
Idulnas, now in possession of Jim's body, would visit the Firehouse in an attempt to trick Ray into coming with him via the threat of lawsuits. Winston Zeddemore challenged his claims, and the possessed Jim stormed off to commune with Gozer's essence from the observation deck at the Empire State Building.
Two days later, in order to draw Ray back to Manhattan Idulnas would animate the bear statue of Wall Street. After the Ghostbusters defeated the newly created Gozerian Terror Bear, Idulnas appeared through the rear windscreen of Ecto-1a and kidnapped Ray. He bound Ray atop the roof of 55 Central Park West and there revealed his purpose, afterwards knocking Ray out with the intention of making Ray's mind easier to influence for the re-selection. However Ray's Spirit Guide got there first. The other Ghostbusters soon arrived and began their offensive, and once Gozer manifested only to yet again be defeated. Soon after Idulnas would vacate the physical plane, promising to return as many times as it would take to achieve its task.
Months later, just before Christmas, Idulnas appeared before an incarcerated Janosz Poha. Idulnas demanded his service, taunting the troubled painter with various threats and promises but Janosz repeatedly refused. Idulnas finally threatened to flay the flesh from his bones, then murder his sister and nephew. Janosz finally relented and allowed Idulnas to posses him. Hours later his cell is wrecked with the walls covered in a spell written in the Gozerian Alphabet, designed to summon The Collectors.
Later still, Kylie Griffin attempted to question Janosz about the spell but Idulnas was not impressed by the young Ghostbusters attempts. Idulnas refused to allow Janosz to reveal their plans, despite his hosts apparent incoherence. While Janosz was technically the summoner, Idulnas could still take control of the Collectors to enact his revenge. Much to his surprise, Janosz regained control and altered the summoning spell so that The Collectors would take Idulnas as their victim instead of the Ghostbusters. Indeed, one of The Collectors would teleport to Janosz' cell and violently yank Idulnas from his unwilling host, finally removing the entity from the physical plane and destroying what remained of Janosz' mental stability.
Idulnas has displayed an array of powers within its short appearance. Having the ability to move across reflective surfaces and use them to kidnapp or posses victims, both alter and manifest through paintings, possession, animation, generate P.K.E. type blasts, shapeshift (to a limited degree), extension, and generate an obsidian creation resembling the Temple of Gozer. It appeared to also have the ability to augment the ambient P.K.E. levels within New York City, hastening the process of Gozer's reform.