Flamespike the Crawler was a Super Unique Razor Spine found in the Inner Cloister in Act I of Diablo II. He is not encountered in the Lord of Destruction expansion pack, though Classic characters may still run into him.
Flamespike was the last Quill Rat of any type found in the game. In the original Diablo II, he and his pack of 5 or 6 minions always spawn in the Inner Cloister area, and are usually the only monsters in that area. A lot of the time they spawn almost directly on top of the waypoint there, making it a bit of a hazard to use the teleporting pad.
Flamespike himself is recognizable by his bluish green decor, and his Cursed attribute. The combination of his Amplify Damage and the ranged quills from him and his minions could quickly become lethal, particularly on higher difficulties.