The Neo-Soviet marine biomods
Classified as a category 4 threat, the Elib is somewhere between a vampire lord and Godzilla for limits of escalation. Yes, I would consider using a nuclear device to kill just one. I am that sure that I want it dead.
While walking through the mountains, emerging from several small crevasse near you and begin attacking the party member with the most exposed skin. The Beez are creatures the size of a fist, with minimal stats but high agility. There is ten or more beez. Their sting causes a immediate loss of hitpoints.