Hell knight doom 3

A giant green demon first seen in delta labs 4 from the portal summond by dr. betruger a scientist in a bio hazzard suit gets out of the portal and then two hell knights come out of the same portal and toss the bio hazzard suit scientist "apparently killing him" and then they see you and go after you. After killing the hell knights you must enter the portal to hell and you come across more hell knights in that level but there is a diffrence in their appearance they seem to be black from burning in lava or some other reason and have bloody limbs "probably from their previous victim". And then you go in another portal to fight the boss the guardian of hell to obtain the soulcube as a new weapon causing 1000 damage and the only way to defeat the games main boss the "cyberdemon" is by using the soulcube exacly 4 times on him. The soulcube also takes some health from the monster hit by the soulcube and gives that stolen health to the player.