The main variation between this Tyrant and other models was the inclusion in its genetic makeup of the Hypnos gene, a modified genetic strand that, when implanted into an organism, would kill the weaker cells through natural selection, leaving only the best to keep the organism ongoing and encouraging the reproduction of the better cells. This gene was created by Sheena Island Umbrella scientist Doctor Klein.
When first seen, the Hypnos Tyrant resembled a genderless, hairless youth with claws for digits, floating in a stasis tank. Once awake, it proceeded to kill one of three people according to the selected scenario: Andy Holland, the sewer janitor, Vincent Goldman, the Umbrella Commander of Sheena Island, or the UT (Umbrella Trashsweeper or UnderTakers) commander. After minutes of fighting against Ark Thompson, the creature mutated into a more aggressive second form, with greater muscles, much larger digits upon its left claw and an enlarged mandible. After a while, however, the Tyrant mutated again.
This final mutation was more of a regression than true evolution, as the beast lost much of its intelligence in the process, suffering through a form of hypertonia, losing its humanoid shape and becoming a bestial, primate-like, hunched monster. Because of the excessive muscle growth, the beast was rendered vulnerable, along with a fissure in its integument covering its right pectoral. This Tyrant model was destroyed when it leapt upon Thompson's escape helicopter, at which point a missile was launched into its abdomen. Seconds later, another missile was launched against it. It is extremely unlikely that it survived the two blasts.
In its original form, Hypnos-T Type resembled a genderless and hairless youth with smooth white skin. The only visible mutations were confined to one arm, which was discolored and slightly larger than the opposite limb, its fingers also ended in small claws that could be used for stabbing attacks.
In the second form, the Tyrant's mutations became more prominent, with a mouthful of fangs and much larger claws on its larger arm. Its muscle mass increased slightly, most notably on the upper body and left arm, with a visible bulge where the heart was beginning to expand. In this state, Hypnos could run at high speeds and viciously slash its opponents. It could also perform a downward strike. Its most dangerous attack was a powerful jumping strike performed at a distance.
In its final form, Hypnos-T Type suffered through a form of hypertonia, becoming a bestial, hunched, primate-like monster. Because of the excessive muscle growth, the Tyrant was rendered vulnerable, with the heart becoming exposed as is common in its brethren; it also lost much of its intelligence, rendering it little more than a wild animal. These new weaknesses didn't make it any less agile, however, and it was able to protect the exposed heart by shielding it with its claws.