His first appearance was in Mystery in Space #60 (June 1960) “Attack from the Tentacle World” making him the first living planet in comics by a couple of years.
He’s a member and founder of a group called the Forgotten Villains (Mister Poseidon, Faceless Hunter, Atom-Master, Kraklow, Ultivac, Enchantress),. He also possess some kind of cybernetic tentacles which gives him a deathly range.
Yggardis Nickname appears to be ”The Sorcerer Planet”, we have seen him in one of Adam Strange adventures, after a time, he made a come back with the Forgotten Villains, in this version his tentacles has changed for something similar (if we can say) to the Doctor Octopus Adamantium tentacles.