Concept doodle thingy for a Basilisk Valekin.
The idea is that Valekins [due to lore] have slightly sorta unstable genes. Basically rather than adapting to a new environment over generations, the Valekins just have a ability to "spontaneously" adapt to the new environment. But this adaptation is constant. In the case of deserts, You can Basilisks form that have petrification venom and breath.

TL;DR
Dry a valekin in a desert to get a snaky boi that makes you rock hard.