Variant of the PK; once killed it spawns 4 AI controlled Riflemen at the same level as the players to fight for them. Once redeemed it starts at the same promotion level as the normal PK, and they level up in tandem; promoting one will promote the other at no additional cost. Variants also do not give XP for promoting, though you still get the normal XP for the base unit since they upgrade at the same time
Due to the fact that PK IFV gets both HP and DPS at each promotion level, how much health it can have at a given equipment level is different for not just each equipment level, but each equipment level at each promotion level. For now you will just see the percent it is increased by and need to figure out what the health should be based on the percent increase and the health the unit will have at its current promotion level.