The Goreslingus Rex is mentioned once in The Incomplete Book of Dragons, when discussing dragon eggs. This dragon is not written about any further.
Though Goreslingus Rex is a rather interesting name, no assumptions can be made from it.
We can determine that the Goreslingus Rex has toxic breath, potent even as an infant.
- "In the same way, a Common or Garden Dragon egg looks horribly similar to the egg of a Goreslingus Rex dragon. But a baby Common or Garden dragon is likely to lick you and think you are its mama, while a baby Goreslingus Rex dragon will send you straight to Valhalla with one snort of its dear little nostrils. (Don't blame the poor baby Goreslingus Rex. It thinks it's being friendly.)"
- ―The Incomplete Book of Dragons
The Goreslingus Rex is mentioned once in this reference book at the opening of a section dealing with dragon eggs.