class 1 - can be killed by standards, few guards, or an immortal.

Class 2 - can be killed by many standards/guards or an immortal.

Class 3 - a whole battalion of guards, with some vehicles, or two+ immortals.

Class 4 - an army of guards, with vehicles, and heavy artillery, and they still will probably lose. 4+ Immortals are recomended.

Class 5 - Another Class 5.

These are just rough estimates.
[@Vandy] gets credit, and a thank you for the idea.