Kathulos is a living planet, just like the other living planet Ego. He has long been seen by the occult world as an evil entity, being of a "wicked something beyond the range of mortal understanding". Kathulos shines powerful necromantic rays that are so bright he is described as "glistening with monstrous fury". With these rays it captures unfortunate victims from light years away and drags them to him in order to absorb them. It is not known how old Kathulos is but it has most likely been around for millions of years.
Kathulos Attacks Doctor Strange
Kathulos was given additional power by the chaos demon Shuma-Gorath to kill Doctor Strange. With this power, Kathulos first sent waves of demons to attack the sorcerer. After Strange defeated the demons he drew the attention of the planet Kathulos. As Strange was gazing upon Kathulos from Earth, it lowered towards the archway of the Lintel Stones of Stonehenge and focused its necromantic rays upon him. In doing so, Kathulos turned the night sky into a burst of flaring radiance that wrapped around Doctor Strange and forcibly dragged him through dimensions until Strange arrived on the surface of Kathulos. As Doctor Strange thought to himself where Kathulos could be, vines stabbed down at him and attempted to strangle him to death. However, Strange was able to free himself with the power of his mystical energy.
After Strange calls out Kathulos, he appears before him as a gigantic flytrap holding a ghostly face within its mouth. Kathulos explains to Doctor Strange that he cannot be defeated on his planet, because he is the planet itself and therefore omnipotent. Doctor Strange fears that Kathulos may be the most dangerous of all servitors of Shuma-Gorath.
Strange attempts to use his magic, but Kathulos is unaffected, explaining that on the planet Kathulos, which he is, Strange's magicks will not work because he will not permit them to. He explains to Strange that on Kathulos he is no more than an ordinary human being, and as such compared to him is weaker than a newborn kitten. Kathulos strangles Doctor Strange with his vines again, almost killing him, but with every ounce of his strength Strange is able to free himself.
The End of Kathulos
Kathulos reveals his most devastating ability by gazing into the eyes of Doctor Strange, leaving him in a paralyzing trance. Kathulos starts to absorb and merge with him as he had done to so many others. However, in doing so Kathulos unintentionally reveals to the sorcerer that his defenses are down while in the process of absorption. Strange takes this opportunity to hurl the Crimson Crystals of Cyttorak at the roots of Kathulos, fatally wounding the planet. Everything on the planet begins to wither and die. Kathulos calls out for Shuma-Gorath to aid him, begging the chaos demon to not desert him in his time of utmost need - but the planet's plea goes unanswered. As a withered stalk snaps a faint wail rises into the alien air revealing that Kathulos is no more.
With Kathulos's death, Strange was left marooned to starve in galactic solitude as Shuma-Gorath had planned if Kathulos was defeated. In order for Strange to find his way toward Earth, he summons all of his mystical strength to destroy the core of Kathulos. With a great explosion, the dead and rotting Kathulos bursts, hurling its remnants all over the galaxy.
Powers and Abilities
Like Ego, every aspect of Kathulos is alive. Each molecule on the planet as well as the atmosphere is controlled by the consciousness of Kathulos - therefore Kathulos is omnipotent on his planet, which is himself. The surface of Kathulos is covered in a jungle-type terrain consisting of vines, grass, trees, and all sorts of alien vegetation. It is unknown what makes up the core of Kathulos but it is likely that it is of a similar makeup to Ego. In addition to Kathulos' ability to control every molecule of itself including the atmosphere, Kathulos can negate the effects of any magic that can potentially harm him while in its environment. Kathulos is able to shine necromantic rays at targets light years away and drag them into its atmosphere, which he demonstrates by forcibly dragging Doctor Strange to him. The deadliest of Katulos's powers is his ability to paralyze his opponent and absorb their soul. However, this proves to be a critical weakness as Strange realized that its defenses were lowered and was able to fatally injure Kathulos with the Crimson Crystals of Cyttorak.