and other ability suggestions
A starting ability for the skulk should be a 1 hit kill akin to CS's "strong" knife attack.
If the idea of skulks to to sneak up on marines, it makes no sense that they have to take a few bites out of them from behind or overhead to finally kill them.
They should have a charge attack (clicking it begins the motion, 1.5 seconds later it attacks wherever the cursor currently is) that instantly KO's a non-armored marine.
Another suggestion would be to have a "camouflage" ability.
Cause the skulk model to phase out while standing still simulating a chameleon effect. Then allow them to move slowly with a slight increase in opacity.