The plague are some short of virus that try to control humanity,they are deadly

1 hatchers

They where once humen until a virus of the plague transformed them into zombies who would use melee weapons like axes,hammers and probably a butcher knife they are mostly common

2 Monstrosity (Image the picture of the guy without the gun and have some black substance leaking out of some wounds)

They are strong very strong as they where made to be strong as they charge like s bull and when they grab there victims they slam them repeatedly like a charger from left 4 dead

3 Hijack (imagine the robot with black substance leaking out of its eyes and mouth)

They are Robotics controlled by the plague,they actually became smart enough to use guns and cover and some of them know how to talk

3 Songmen
There robotic MK5s construction worker with some black roots across it's body since they where build with 'Hardwire' network so the roots of the plague controls it muscles and destroyed its voice box,it has a microphone that when it saw victims it scream into the microphone,to called in a horde of Hatchers

4 Infector (the blood will be he black substance)

Once workers to the CIC (Center for Infectious containment) now they are nothing but bags of gas that if you shoot and kill it it release a black substance gas that will infect anyone that inhale it but don't worry stay out of the gas as it will disappeared after a moment or two

5 Hacks (imagine that roots are black)

With the plague controlling its muscles they are not good at seeing but they are good at hearing,be nice and quiet otherwise you'll face a horrible group of them.

Bonus

Mr V (experiment 570)

Mr V is founder Angel's personal 'nemesis' as he is taller then any person (and your oc) he has incredible strength and can smash through walls but he is slow,he is unkillable but he can be stun and plus he can easily kill your OCs (If you want him to kill your OC) and he is immune to all type of viruses and diseases including the plague virus