Starfinder: Xenomorph Boiler

Chris Van Deelen

Xenomorph Boiler (Combatant) CR 1 XP 400

Neutral medium aberration

Init +2; Senses Blindsight (sound) 60 ft.; Perception +0


Defense                                                             HP 20

EAC 11; KAC 13

Fort +3; Ref +3; Will +3

Defensive Abilities Acid blood, acid splash explosive; immunities Acid, cold, vacuum

Weaknesses Vulnerability to fire



Speed 20 ft.

Melee Bite, +8 (1d8+5 P) or two claws +4, (2d6+5 plus grab S)

Offensive Abilities Grab, inner jaw, trip



Str +4; Dex +2; Con +1; Int -4; Wis -2; Cha -2

Skills Acrobatics +10, Athletics +5, Stealth +10 (+15 in hive)

Languages None

Other Abilities Stalker

Gear None



Environment Any

Organization Solitary or small groups (1d4)


Special Abilities

Acid blood (Ex) The blood of the Xenomorph is highly acidic. Whenever it bleeds, the blood will burn through almost any substance and will cause 1d4+1 points of damage. The blood will continue to burn for 1d6 rounds, causing damage each round. Attacking the Xenomorph with natural weapons is a very poor idea as the target automatically suffers the acid blood damage if they are using slashing or piercing attacks.

Acid Splash (Ex) Whenever the Xenomorph is hit by any type of attack which deals more than 10 points of damage in a single strike, the blood will have a chance to effect anyone near. The acid splash has a radius of 20 ft. and those caught in the area of effect are allowed a Ref save (DC 10) to avoid taking damage. If the save fails, the victim will suffer 1d4+1 points of damage per round, for 1d6 rounds.

Explosive (Ex) The creature is fragile, and its acidic blood seems to be under heavy pressure. Whenever the creature suffers 10 or more points of damage, it will detonate. The radius is the same as the acid splash and causes the same damage, but the exoskeleton fragments also inflict hideous damage, causing 3d4+1 points of damage. A Ref save (DC 10) will result in half damage.  Strangely enough, other ‘boilers’ are immune to the acid and the explosive exoskeleton effects.

Grab (Ex) When the Xenomorph happens to be within range of a hive, it will often attempt to grab and drag a victim back to the hive to be cocooned and impregnated. The creature must make a claw attack, it will do normal damage. If the attack roll successfully hits the target’s KAC +4, the creature automatically grapples the foe as a free action. (If it hits the targets KAC +13, it instead pins the target). If it succeeds, the creature will then drag the victim back to the hive to be used as a host. The victim can attempt to break free while grappled, requiring a successful escape (using the acrobatics skill). If the victim turns out to be ‘troublesome’ the creature can opt to bite in order to make the target more ‘compliant’.

Inner Jaw (Ex) Possessing an additional ‘jaw’ the creature can opt to use this attack. It typically will use this on a grappled target, or it can opt to use this in addition to the bite. The bite does slightly less damage (1d6+5 S) but is more accurate. The creature has a +11 with this particular attack, and if the target is grappled, then the bonus is +14.

Natural Weapons (Ex) Cannot be disarmed.

Stalker (Ex) The Xenomorph is a near-perfect predator. As such it gains a +5 racial bonus to stealth rolls, and whenever the creature is in a hive, this bonus increases to +10

Vulnerability to fire (Ex) The creature has few vulnerabilities, and fire is one. Whenever it encounters fire, the creature will take an additional 50% damage (rounded to nearest) and suffer a -4 to any saving throws involving fire.


A very strange version of the Xenomorph has been dubbed ‘Boilers’ by those who have encountered them. These particular versions of the Xenomorph acted much in the same way as the others that they had encountered, and when they encountered groups, would quite literally explode, typically taking those hapless individuals with them.

If one takes the time to inspect the creature, they will discover that the Xenomorph is covered with boils that appear to be filled with the creature’s acidic blood and they have a strange silver sheen to their exoskeleton. They are also quite a bit slower than their brethren, and walk with a strange, seemingly painful gait.  And unlike others of their species, they seem to be incapable of climbing or clinging to any surface. They can only walk on the ground.

Unlike their un-mutated brethren, these creatures are fully blind and only react to sound. If someone moves very slowly and makes little to no sound, that person can move within inches of one of these strange creatures and not be noticed.

It is not known how, but other Xenomorphs, particularly the Queen and Praetorean Xenomorphs are able to control these mutated creatures and often place them in the hives in strategic locations in order to act as living mines, set to detonate whenever groups of intruders (or even single intruders) are located.

It has been speculated that these are the elderly versions of the Xenomorphs, but evidence suggests otherwise, since rumor has it that there have been specimens discovered in a state of hibernation that are easily thousands of years old. Others speculate that they are suffering from a natural mutation that renders their exoskeleton far thinner than the others of their kind, and as such they are nowhere near as effective in combat or of that much value to the queen.

When they do engage in combat if they suffer more than 10 points of damage from a single attack, they will explode. This will not harm other Xenomorphs around them, but can be devastating to non-xenomorphs.

They can still attack in combat, and will do so, unless they hear more than two or three targets. They will use their claw and bite. Oddly enough, they will never use their tails in combat. If there are three or more targets in range, they will suicide and explode.

Aliens, Predator, Thing Collection

Starfinder Creature Index

Chris Van Deelen is the creator and contributor to over half of the Wisdom from the Wastelands series, contributor to the Swords of Kos: Hekaton anthology. He also wrote Creatures of the Tropical Wastelands, and 100 Oddities found in a Car. As prolific as he is, Chris Van Deelen continues to write and produce material which will be in publication soon. Not only is he a prolific content creator, he also has a wide selection of fiction and stories! If you like his work, please follow his personal author page on Facebook and on Twitter to keep up with his latest news and game content.