There are 4 evolves which you can upgrade from level 1 to level 20 (if level 20 appears on your profile).

2k gold, 5k gold, 10k, 15k, 20k, 25k, 30k, 35k, 40k, 45k, 50k for 10-20 (max). Total gold required to max an evolve: 727,000 gold.

Death resistant: Increases HP by 1.5% per level purchased.

This is very useful when paired up with armour that has high HP.

Enhanced reflexes: Gives you xx chance to not take damage.

Kamikaze: Increases damage when shield is exhausted by 1.5% per level purchased.

Quite good, this should be the last evolve you max out in my opinion.

Piercing rounds: Gives a chance to ignore enemies' shields by 1.5% per level purchased.

This evolve is excellent! Who doesn't like havering xx chance for a one shot kill any armour with the Black Mamba?

credit to: HEROpVp (forum Moderator and player)