Like other rulers, he performs one action after every action made by any XCOM squad member, during a special "Ruler Reaction" phase.
- He can use Tongue Pull like other Vipers, binding a soldier with a fifty percent chance to knock them unconscious with every tick.
- As others Vipers, he can also use an area-of-effect breath ability but instead of poison, he spits out a cloud of gas which freezes units caught in it for two turns.
- He will summon a psionic rift after a few turns, or after taking too much damage, and attempt to escape. If he does so, XCOM will encounter him again in a future mission, with the remaining health he had when he escaped.
- Completing the Viper King Autopsy unlocks the Serpent Suit, an armor based on his appearance and abilities.
- He is the first and only male Viper encountered.
- Once killed, the description mentions that he was already reproducing with the female Vipers, despite being only recently hatched.
- There is a glitch where if you kill the Viper King the mission you encounter him, you will not get the corpse.
- Ending turns will not trigger the defrost tick on Alien rulers. This makes it possible to completely shut down a ruler by only attacking with Lightning Hands and ending turns to refresh the cooldown.