special: drops 15 health
The pyro is a close range attack force for the enforcer team. At long range they can be picked off easily by the player. At close range a full-on blast from the flamethrower can be very damaging. In addition, the flames will fill small corridors and rooms, distracting and disorienting the player.
Pyros will infight with other base monsters, and their attack covers such an area they are likely to hit something when placed in mixed groups.
On the other hand, pyro flames will not damage other pyros, increasing the effectiveness of groups comprised solely of pyros. Multiple pyros in a single location will make it very hard for the player to see anything, so care should be taken.
The flames are stopped by water, so giving the player a pool to dive in near pyros will make them easy to handle.
Additionally, the biosuit powerup will endow the player with the same flame-retardant property the pyros themselves enjoy. However, only the player’s health will be protected – their armour will still be burned away by the flamethrower.
The pyros are slightly odd in that they wield a weapon with no equivalent in the game. The closest approximation would be an area effect lightning gun. This unfamiliarity makes them a little harder to understand, for players and mappers.
The most useful thing to consider with regards placing of pyros is that the low damage coupled with high rate of fire of the flames has the consequence that if the player is wearing any armour at all, it will deplete far faster than their health. In fact, no health points will be lost at all while the player retains some red or even yellow armour.
Add to that the 15 health each pyro drops upon demise, and what you have is an enemy unlikely to leave the player seriously wounded but quite possibly naked. The pyro is an armour-stripper.
See kellbase1 for this effect. The 4-pyro combat in the rusty basement most likely removes any GA left on the player after encountering the 3 edies above. Once they leave that area and climb the ladder to the ventilation section, even a handful of vorelings in the dark can make the player feel vulnerable because they only have their health to survive on.
How best to make use of this in your map is somewhat oblique, but it can be useful to burn away what armour the player has left after a combat so the next armour they find in the map is sure to be acquired, and even welcomed. It also allows the arc of increasingly powerful items to be varied, so the player doesn’t simply advance uninterrupted from green to yellow to red over the course of a map.
The short range but broad area of the flamethrower means you want to keep the pyros for smaller areas. They’re not snipers. Instead, they can act as interdictors, aggravating the player’s attempts to progress down narrow corridors and walkways, or grouped in rooms around vital items like keys.