Guide to some obscure xeno mechanics

This is not a new player xeno guide. This is intended for players who are somewhat experienced but have not yet learned all the details of some weird and obscure mechanics. Mainly it’s for stuff I don’t see explained anywhere else that a lot of people seem to have misconceptions about.

What seems simple at first glance actually does have a bit of complexity to it. Every xeno caste has a tackle range and a tackle chance. When you have tackled a target enough times to be within the range, you roll the tackle chance for each tackle. If you don’t get it by the highest point of the range you will automatically tackle them down regardless of chance.
For example, for a drone with a tackle range of 2-4 and a chance of 35%, each individual tackle will have the following chance of stunning a marine:
1st tackle - 0%
2nd tackle - 35%
3rd tackle - 35%
4th tackle - 100%

Once a marine is tackled down the counter resets and your next tackle will count as the 1st tackle. Stuns also reset the counter, this includes short stuns like sentinel scatterspit or crusher stomp. If a marine is infected you can keep tackling them once they’re down and each tackle will automatically restun them.
Tackles are individual to each xeno and do not stack, meaning if one xeno tackles someone twice and another xeno also tackles them twice that does not count as 4 tackles, each xeno is tracking their own individual tackle count. Also worth noting if you don’t tackle them for a while the counter will reset.
A lesser known mechanic is tackle strength. Each xeno caste, in addition to their tackle range and chance, has a tackle strength range that determines how long the stun lasts for. A lot of people know that drones have better tackles than warriors or defenders, but a lot of them don’t realise that the reason the drone tackle is better is because it’s strength is higher, meaning once a drone takes someone down they can drag them away without them standing up again. This is more important than you might think.
Here are the values for each caste:

Tackle values for each caste

Drone 2-4 range, 35% chance, 3-4 strength
Hivelord 2-4 range, 45% chance, 4-5 strength
Carrier 2-4 range, 50% chance, 4-5 strength
Burrower 3-5 range, 40% chance, 4-5 strength
Runner 4-5 range, 40% chance, 4-4 strength (has fast attack speed though)
Lurker 2-6 range, 35% chance, 2-3 strength (has slow attack speed)
Ravager 2-5 range, 35% chance, 4-5 strength
Defender and Warrior 2-4 range, 35% chance, 2-3 strength
Crusher 2-6 range, 25% chance, 2-3 strength
Praetorian 2-5 range, 45% chance, 2-3 strength
Sentinel 4-4 range, 4-4 strength
Spitter 2-6 range, 45% chance, 4-5 strength
Boiler 2-6 range, 25% chance, 3-4 strength
Queen 2-6 range, 55% chance, 5-6 strength
Lesser Drone 4-5 range, 35% chance, 2-3 strength


  • Certain castes with high tackle strength and low maximum range (such as drone, runner and sentinel) can keep marines stunned indefinitely if they keep tackling. You can potentially drag them all the way back to the hive if you are scared of reverse bursting, which has the added effect of making marines REALLY salty in looc.
  • Castes like Lurker, Crusher and Lesser Drone will really struggle to keep a marine down unless they get amazing RNG. As lurker your best way to solo cap is straight off a pounce. Pounce, grab, start devour, then tackle twice and hope you get that 35% chance (and curse morrow for removing the ability to tackle with crippling slash… :cry:)
  • Don’t use short stuns if someone is in the middle of tackling someone down, you are not helping. THIS MEANS YOU SENTINELS, PLEASE GOD STOP SCATTER SPITTING WHEN SOMEONE IS 1 TACKLE AWAY FROM A STUN.
  • As a runner you can’t use the pounce, attack twice, pounce again strategy for capping as the pounce resets the tackle counter each time and you need a minimum of 4 to cap.

Reverse Bursting
This one is a bit of a noob trap if you don’t understand how it works. Each time a marine attacks from inside you while devoured there is a chance for them to reverse burst, equal to this formula:

  • 4*(100*brute damage/maxHealth - 75)

What does that mean in practice? At 25% hp or above there is 0% chance to burst, you are fine. Once you get below 25% the chance starts to increase, and reaches 100% chance at 0% hp. 20% hp would have a 20% chance to burst. 15% hp would have a 40% chance to burst. And so on.
Also this is probably obvious but marines will do more or less damage depending on their weapon. A knife won’t do much, but a machete or an SMG with stock+bayonet can kill you way quicker than you expect. Always watch your hp when you have someone devoured and regurgitate them before you reach 25% hp. Most xenos that die to reverse bursting do so because they assume that as long as they are above 0 hp they are fine. Don’t make that mistake, just remember that 25% hp is the danger zone.

  • As mentioned earlier, if you are a caste that can indefinitely keep someone stunned (such as drone, runner or sentinel) you can just not devour if you’re willing to drag them all the way to the hive. Obviously this isn’t viable if you’re a backliner that needs to tunnel though.
  • If a marine has a weapon like a machete and is doing a lot of damage to you you can regurgitate them, tackle them down again (which makes them drop their weapon) then devour again. Just make sure you actually tackle them down before the stun wears off and they PB you. Remember, lurker tackles suck ass, so this isn’t so viable as lurker.
  • Don’t be afraid to just drop the cap. It’s better than dying. If you drop them in hive territory surrounded by doors you can probably recap them anyway, either alone by healing and fighting them again or by calling over some other xenos to help.

Limb targeting
Technically limbs are a marine mechanic but it’s nice to know how they work as xeno so you can make a proper decision on where to target. The damage formulas in this game are kind of complicated so I won’t get into too much detail about the specific formulas and such.
Each body part has a maximum damage value it can take as well as a minimum fracture damage. Any damage that would cause the part to go over the maximum will instead spill over onto the next part in line (eg hand damage spills over to arm). Max damage also affects delimbing, in order for an attack to delimb the limb must already be at maximum damage, and the % chance of a delimb is reduced by the maximum damage value. Minimum fracture damage is simply the minimum amount of damage that body part needs to have before it’s possible to fracture it.

Limb values

Chest and groin:

  • Max damage 200
  • Min fracture damage 30

Legs and arms:

  • Max damage 35
  • Min fracture damage 20

Hands and feet:

  • Max damage 30
  • Min fracture damage 20


  • Max damage 60
  • Min fracture damage 30

Another thing to know about is armor. A lot of this information is available on the wiki but something you might not know is that a marine’s uniform provides them with 10 melee, 10 bio and 10 internal armor, which stacks on top of the values from whatever chest armor they are wearing.
Hands, feet and head are only covered by gloves, boots, and helmet respectively, which makes them the most vulnerable in almost all cases. Arms, legs, chest and groin are all covered by both chest armor and uniform, making them the tankiest. Note that even when they are wearing light armor, hands/feet/head are still the most vulnerable.

Here I’ll go over the pros and cons of targeting each body part:
+ Low armor, so you deal maximum damage
+ Some marines don’t wear helmets, meaning even more damage
+ Can deal eye and brain damage, although these are arguable the least useful organs to damage
+ Chance of decap if you’re lucky, although it’s rarer compared to hands/feet/arms/legs delimb and a helmet will block 1 would-be decap
- Takes more damage to fracture than most other limbs, except chest and groin
+ Low armor, so you deal maximum damage
+ Easiest to fracture, technically slightly easier than feet since gloves have lower internal armor
+ Easiest part to delimb, along with feet
- Can’t get internal bleeding
+/- Fracture makes marines drop things rather than the larger slowdown other fracs give. This can be useful but may or may not be as good as a foot fracture.
+ Low armor, so you deal maximum damage
+ Easy to fracture
+ Easiest part to delimb, along with hands
- Can’t get internal bleeding
Same as hands/feet, but with the following tradeoff:
+ Can get internal bleeding
- Same armor as chest, so less damage
- Delimb is less likely
- Harder to fracture, both due to higher internal armor reducing the chance and higher melee armor making it harder to reach the minimum damage
+ Potential for organ damage, with lungs, heart and liver
+ Can stack damage more easily with abilities that always target chest, like defender headbutt
- Heavily armored, so less damage (matters less if they have light armor)
- Hardest to fracture, along with groin
+ Only contains 1 organ (kidney), meaning all organ damage gets concentrated onto that 1 organ. Deadlier to have 1 heavily damaged kidney rather than 3 slightly damaged chest organs.
- Same downsides as chest

Also worth noting for limb targeting that you don’t always hit the selected limb, it’s a 70% chance to hit what you want. If that chance fails then it picks a target randomly, although it’s weighted to be more likely to hit larger areas like chest.

That’s all I’ve got in this guide for now, might add more to it in the future.


This is a good read.

an extra benefit to targeting feet for slashing is that acid spray effects break foot splints instantly.

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Honestly, limb targeting is the biggest deal breaker for a xeno.

Xenos not knowing where to slash, and just going for the chest, make a huge difference between getting easy 2 slash delimbs or quick kills versus wailing on some guy for 12 slashes and failing to even make a dent. More people that know to aim for hands/feet/unarmoured head, the better for xenos.

Conversely, my marine main mind must emphasize to all xenos to exclusively target the chest, especially against marines wearing heavy armour.