Unvanquished is an open-source FPS game featuring team-based strategy and RTS elements, pitting humans against aliens in a futuristic setting.
https://forums.unvanquished.net/
What if humans who've killed aliens worth at least 60 evos and made it to S3 without bleeding become saint: there's a barrier impenetrable for aliens around them and all the shots they fire set things on unquenchable fire?
What if ... suddenly narwhals?
Maybe you could allow them new reinforcements/items better than the normal ones available. Possibly invincibility for a period of time. Or upgraded weapons. I'm not sure but this idea could work if it is altered a little to ensure fairness. Remember if you enable such an advantage for a human, an alien must also have an equal good skill. Possibly a greater evolution allowing the larger aliens to climb walls or even stronger armour on their bodies.
F3 for now until we can find something that works
How bout as you kill whore, you build up a meter that once it fills up, you can use it like an invincibility star that lasts 5 seconds and insta-kills whatever you touch, except your teammates, something like what the buff banner is used from TF2. That would be ultimate base rape. The meter diminishes upon death.
But seriously, I don't see a point for this.
It could work as a last resort if your base is being destroyed
Oh, great! Lets reward invincible humans who have proven that they don't need any other help by making them even harder to kill!
No, Humans who've killed aliens worth at least 60 evos and made it to S3 without bleeding get to be reborn on their next death.
The next time they spawn they grow wings so they can fly around. They also get a little force field and tuck up into a little ball and roll around.
like this but human and with wings.
les make F summon jesus
he is invisible and shoots surprise humans 
Jesus is always with us no matter what.
We could trial this and discuss it later