Changelings

[Sundance]

Stuff

Pretty much hit the nail on the head.

How about this
Fire is an abominations worst enemy, they take virtually no damage from brute, but fire hurts them, stops them from healing quickly. This is such a great addition to abominations because it makes them horrible monstrosities that you WANT to run away from.

Fire pretty much cancels out the lings speed regenerate, so why doesn't being on fire cancel out the acid spit too?
This is good because not many people have access to fire (security do if you know how) and it would encourage people to arm themselves with fire. It wouldn't be a huge nerf towards the ling, the ling still has his sting (along with any other arsenal it has), and can go abomination (in which he can spit acid) if he has enough dna.
It just means that someone who is prepared to fight a ling, will be able to, or at least will be able to defend themselves in a fire-fight against that annoying homing sludge missile.