As of right now, mutators are mostly flat out stat bonuses, this thread was made to discuss and suggest changes to xenos mutators that are more unique. I'll try to edit all of the suggestions under their relevant castes. keystones and unique mutators will be included in the list, and most of my information is from the wiki.
24 Points per xenos in total, 30 with flaw, 6 per level - Young, Mature, Elder, Ancient.
(?) - Don't know if the caste is able to get the mutator.
(H) - Hive Mutator.
(K) - Keystone, can take only one.
All Xenos
(K) Regenerate off weeds - It allows a xeno to heal and regenerate plasma as if they were on weeds even if they aren't.
(K) Siege Claws - this keystone allows any xeno to increase their damage against structures like barricades or Sentries, but trades off damage done against lifeforms like humans. While it would work best for xenos that don't often slash at humans, any xeno can use it effectively, although they will sacrifice killing power as a result, meaning you have to decide if you want to be more support-focused or combat-focused when considering this keystone.
(K) Hunting Claws - This Keystone increases the damage done to lifeforms like humans, but results in reduced damage against structures. The mirror opposite of Siege Claws, this keystone is capable of making xenos deadlier in combat against marines and Yautja alike, but also makes breaching defenses much more difficult due to the reduction in damage to structures. Such a keystone can make a drone a tad more deadlier to face off against, but without siege-focused xenos on your side, damaging barricades will be a hassle.
(K) Reinforced Armor - A keystone that gives xenos a decent boost to their general armor, as well as making them more resistant to explosives, allowing them to endure damage they couldn't before and then some. The tradeoff is a loss in speed and a reduction in pounce range due to their weight. When choosing this, a xeno has to decide if they value agility or durability.
(K) Heightened Telepathy - Allows xeno to send and receive hive mind messages to other xenos with this ability even if the queen dies, as well as use the psychic whisper ability.
T1 Xenos
Drone -
(K) Faster Weeds - Boosts weed growth speed and spread radius.
(K) Acid Tipped Claws - Reduces your brute damage and applies the reduction amount as burn damage. With this keystone you do brute and burn damage on each slash.
(K) Plasma Network - This unit is capable of transmitting plasma to her sisters that are in her sight and on weeds.
15X15 range for tranferring plasma, increased plasma cost for transferring? unable to spam plasma transfer? non-keystone?
Defender -
Sentinel -
(K) Acid Tipped Claws - Reduces your brute damage and applies the reduction amount as burn damage. With this keystone you do brute and burn damage on each slash.
Spread Shot - Replaces the standard spit with a tight spread tri-burst, which pretty much is like giving a xeno an acid/neruo shotgun that is effective when dealing with crowds. However, choosing this keystone not only makes spits cost 3X as much plasma per shot, but also reduces the range of stun spit by 1 tile, and acid spits suffer a MASSIVE range reduction (to the point that it shares the same range of stun spit). Pretty much transformed a ranged caste into a close quarters fighter
Runner -
(K) Longer Pounce - Increases the pounce range by two tiles.
T2 Xenos
Burrower -
(K) Faster Weeds - Boosts weed growth speed and spread radius.
Seismic Sense - Your senses sharpen and you can feel the tremors of your surrondings.
The burrower and friendly xenos in a 20x20 radius gains a function indentical to a Motion Detector (because hivemind), and increases his vision by five while he is burrowed (20x20).
(K) Hunter Glands - You burrow to your location quicker, and can ensnare your prey for longer.
Burrower burrows quicker (50%?) and has less cooldown, and stuns from burrowing underneath a human are longer (2-3 seconds?)
(K) Earthbound - You dig in on your surface.
Gain stun resistance/immunity, cannot be pushed around.
Carrier -
(K) Faster Weeds - Boosts weed growth speed and spread radius.
(K) Increased Storage Capacity - Increases Carrier storage capacity by 3 for facehuggers and 2 for eggs.
Hivelord -
(K) Faster Weeds - Boosts weed growth speed and spread radius.
(K) Acid Tipped Claws - Reduces your brute damage and applies the reduction amount as burn damage. With this keystone you do brute and burn damage on each slash.
(K) Plasma Network - This unit is capable of transmitting plasma to her sisters that are in her sight and on weeds.
15X15 range for tranferring plasma, increased plasma cost for transferring? unable to spam plasma transfer? non-keystone?
Lurker -
(K) Longer Pounce - Increases the pounce range by two tiles.
Spitter -
(K) Acid Tipped Claws - Reduces your brute damage and applies the reduction amount as burn damage. With this keystone you do brute and burn damage on each slash.
Spread Shot - Replaces the standard spit with a tight spread tri-burst, which pretty much is like giving a xeno an acid/neruo shotgun that is effective when dealing with crowds. However, choosing this keystone not only makes spits cost 3X as much plasma per shot, but also reduces the range of stun spit by 1 tile, and acid spits suffer a MASSIVE range reduction (to the point that it shares the same range of stun spit). Pretty much transformed a ranged caste into a close quarters fighter
Warrior -
T3 Xenos
Boiler -
(K) Acid Tipped Claws - Reduces your brute damage and applies the reduction amount as burn damage. With this keystone you do brute and burn damage on each slash.
(K) Wider Gas - Increases Boiler gas radius by 1 tile.
(K) Bio-Mortar - The boiler can fire over over walls and buildings. Less accurate than traditional direct fire, the target zone is indicated by acid drops appearing on the target tile to give fair warning. Boiler must be under open sky to use this.
(K) Acid Rain - The boilers gas clouds no longer land on the ground but instead disperse in the sky above the target area and rain the choose gas down below, deals far less damage/chemical buildup per tick but is more persistent. Doesn't block LoS.
Crusher -
(K) Faster charge buildup - Crusher's charge will start building up 1 tile sooner and will build up a bit faster.
Praetorian -
(K) Acid Tipped Claws - Reduces your brute damage and applies the reduction amount as burn damage. With this keystone you do brute and burn damage on each slash.
Ravager -
(K) Longer Pounce - Increases the pounce range by two tiles.
Queen -
(K) Faster Weeds - Boosts weed growth speed and spread radius.
Increased Egg Production - Faster egg production.
(H) Infusion of Larva - Gives the hive an additonal 5 stored larva, hive mutator, one-time purchase.
(H) More Leaders - Adds additional xeno leader slot(s), hive mutator.
(K)(H) Faster Maturation - The hive matures at a faster rate, hive mutator.
(K)(H) Resilient Larva - Larva gestate faster and there's a small chance of getting an additional larva, hive mutator.
(K) Acid Tipped Claws - Reduces your brute damage and applies the reduction amount as burn damage. With this keystone you do brute and burn damage on each slash.
(K) Plasma Network - This unit is capable of transmitting plasma to her sisters that are in her sight and on weeds.
15X15 range for tranferring plasma, increased plasma cost for transferring? unable to spam plasma transfer? non-keystone?