From CM Wiki

Pheromones are an aura-based buff available to the Drone, Hivelord, Carrier, Praetorian and Queen. There are three types of pheromones, Recovery, Warding and Frenzy, with effects and range scaling on the caste and upgrade level of the xeno emitting them. If two castes in range are emitting the same pheromone, the stronger pheromone will override the weaker one. If they are emitting different pheromones, both will be applied.

Pheromones require a steady amount of plasma to sustain, although all castes that have access to them usually have comfortable plasma reserves. It should be noted however that they will seriously dent plasma regeneration if used frivolously and should be turned off if not needed. It also costs a bit of plasma to start emitting pheromones. If you run out of plasma, you will immediately stop emitting pheromones.

Your pheromones will stop emitting if you end up falling into critical health with them emitting, but you will still be affected by pheromones from other conscious xenomorphs.

Note that same type pheromones do not stack but varied ones do. e.g. Recovery and Warding.

List of Pheromones

Pheromone Effect
Recovery Pheromone.png
Increases health regeneration, increases plasma regeneration on weeds, reduces stun times of affected Xenomorphs.
Warding Pheromone.png
Grants a reduction in armor taking damage, can also slow and even prevent crit bleedout for Xenos. Additionally provides a small health boost to critically wounded xenomorphs. Potent enough warding pheromones will completely negate bleed out and improve damage reduction to armor.
Frenzy Pheromone.png
Increases movement speed and damage from slashes.

Pheromones Tactics

  • The more powerful the caste emitting is, the stronger the effect. There is an obvious difference between the pheromones of a Young Drone and the pheromones of an Ancient Empress. A well placed high level pheromone can allow Xenomorphs to unlock their full potential in a specific area.
  • Pheromones emitted by a stationary Queen are additionally applied through all Xeno Leaders in existence. These can be located by the star on their XenoHUD Status. They will emit identically to a Queen overwatch, and stack with any other pheromones emitted by the leader.
  • A common pheromone duo is the Queen with a Praetorian emitting Warding and Recovery, with Frenzy left to the next best caste. This allows the Xenos to soak up large amounts of damage and recover their wounded very fast, making for better odds in large, messy stand-offs.
  • Reducing or negating critical bleedout might sound like a lame effect, but it can actually be critical in big battles. A Xeno shot into critical has a life expectancy numbered in seconds, but a strong enough Warding pheromone can make it infinite as long as they don't take further damage, making it trivial to drag them to weeds to let them recover.
  • Recovery pheromones will usually not grant more plasma than they take away to maintain. Of course, this is offset by the fact that all castes around you get said plasma for free, and that everyone gets extra health regeneration if damaged.
  • It is actually perfectly debatable what pheromone is best if you are alone, but they are all useful. Frenzy makes you move faster and gives you a good desperation attack if ambushed. Recovery allows you to recover faster from stun sources like explosions or electrified gear, allows you to heal if tracked down and pays for itself partly. Warding allows you to soak up sudden gunfire while you scramble for an exit. Probably the worst choice is simply no pheromones.