Wall climb. The Xenomorph can climb on any surface without a skill check

Extreme senses. The Xenomorph cannot be attacked from behind and can hear players footsteps if they are running or walking. 

Acid Blood. Any attacks made against the Xenomorph will deal 1d6 acid damage or 1d4 if players succeed a Dexterity 10+ skill check.

Grapple. The Xenomorph grabs the player closest to him. the player is grappled but can escape with a Strength DC 5+ skill check. 

Slash. Melee Weapon Attack: +3 to hit, reach 4 ft., 1 target. Hit: 10 (1d10 + 3) Slashing damage. 

Tail stab. Melee Weapon Attack: +4 to hit, reach 8 ft., 1 target. Hit: 15 (1d12 + 5) piercing damage. 

Head Bite. Melee Weapon Attack: +5 to hit, reach 2 ft., 1 target. Hit: instant death. Piercing damage. (Target must be Grappled)