An new evolution
My idea is an upgrade for the Crag. It is called absorb.
What it does is easy to explain, it absorbs the first DMG done to an Alien and then hast the same cooldown like regen has till it's reactivatet.
So if a skulk has absorb he wouldn't get DMG from 1 LMG shot, 1 SG shot, 1GL hit, 1mine and 0 against Flamer.
The idea behind this upgrade is to beef Skulks in late game but not OP the other lifeforms. Because 1 LMG shot on the onos and his protection is gone.
The Lifeforms that get beefed by Absorb are are only the fast agile ones Lerk/Skulk/Fade (if facinng SGs).
In early game it would only help against mines, because every marine wears a LMG --> 20 R/s, it doesn't matter if he needs 9 or 10 shots.
The only real contra is that SG early game will need 2 shots for Skulks and the Fade could survive 1 more SG shot if he faces a lone marine.