DC is giving away free non-fungible tokens (NFTs) of its superhero comic book covers to people who register for its October 16th FanDome event. The NFT drop— the first for DC— is set for October 5th, and those who register for FanDome will receive one free, randomly-selected NFT, and become eligible for a second free NFT if they post about their first one on social media.

The NFTs will come in three levels of rarity; common, rare, and legendary, and will include Batman, Superman, Green Lantern, Wonder Woman, and Harley Quinn options.

DC is working on the NFTs with Palm NFT Studio, which the comic maker chose for its “environmentally sustainable and energy efficient” technology, which let the company mint “millions of NFTs for fans with near zero cost,” according to a news release. The companies aren’t saying how many comic-book cover NFTs are planned. “This drop pays homage to our 87 year history while visualizing a future in which NFTs play a foundational role in novel ways of interacting with DC content and unlocking new experiences,” DC’s Jim Lee said in a statement.

Last year’s virtual FanDome, the first ever for DC Comics and Warner Bros., provided first-look trailers for Zack Snyder’s Justice League, Wonder Woman 1984, The Suicide Squad, and Robert Pattison’s turn as The Batman. It drew an estimated 22 million views.

This year’s lineup is expected to include a new trailer for The Batman, as well as previews of upcoming movies Black Adam, The Flash, and Aquaman and the Lost Kingdom, new details about the next seasons for its shows Harley Quinn, Batwoman, Superman & Lois, and Sweet Tooth, and the next chapter of the Fortnite — Batman crossover.