PHAcid

PHAcid is an alien from Tech 10: Rebooted.

Powers
PHAcid constantly leaks highly corrosive acid from his metallic bone structure, giving him near invulnerability to physical attacks. He can shoot the acid in streams, allowing him to melt through just about anything. It should also be noted that, even if a lifeform is resistant to his acid's corrosive efects, the acid actually seems to be neurotoxin, causing paralysis that could be permanent when ingested. How and why they found this out, I really don't know. His wings can be used for gliding, but not actual flight.

Appearance
PHAcid is a humanoid alien with a somewhat skeletal appearance, because he's a walking skeleton leaking acid. The membrane of his wings is darker than the rest of his body, due to being hardened acid, which is surprisingly lightweight and comfortable. Provided you're completely acid-proof. He wears green armor on his extremities to prevent accidently melting people's faces off. Note that this will not protect you if he purposefully tries to melt your face off.

Weakness'
If his acid isn't strong enough for the job, he can't adjust it to make it stronger. This also works the other way around, as this is one of the hardest aliens to give a hug to. There was actually a scientific study about his. Why? Because scientists are strange, strange people. Also, if he's attacking you, just throw some baking soda onto him. Nothing bad will happen to you whatsoever.