Cool concept and great artwork.
But I hate to inform you on it's 2 major drawbacks.
1. There is no synergy at all.
- There are unique and well thought out abilities (Innate and Chameleon)
- But these don't really work with any of his other abilities.
2. His other skills are nothing Special.
- Ultimate is a slower cast (hence more painful) version of Feral Scream (Cho'Gath).
- Seeing he is a Melee Bruiser Champ, one would assume that more then one of his abilities would help
him chase down his target / Slow / Increase his movement / Enemies Movement respectively.
However!
These Flaws can be polished out and fixed with some helpful input

so....
Innate - Leave it, this works well on a melee bruiser champ.
Q - He has a Scorpion Tail, which would make one assume it will poison an enemy?
- Poison = Slow, DPS, Blind, Silence Pick one and make it synergize with him.
W - Generally W and E spells will synergize with either the Champions Innate or Q/R ability.
- This has nice Gank potential, but perhaps Form this with his Innate ability and add a brand new skill
altogether.
- I suggest an ability that grants him bonus damage/ armour penetration against a poisoned target.
E - This is a cool skill, adds splash yet works well with this champ.
- However add a secondary effect that synergizes with a new ultimate.
R - Ultimate is very boring, it is just an unessential nuke on a champion that will rarely be stopping to cast.
- Add it to a short cooldown, damage buff that also reduces nearby enemy damage and armour when cast, stackable (in otherwords works sort of like Rageblade, where you need to keep casting for it to stay at its max output)
Make / Consider these changes and create Quervas into a brutal killing machine.
Also if you have time, please do a review of my Champ
Savage Schafer, The Smoke Demon