Envenomer Help

My Envenomer Archetype needs some help, but i'm not sure if it's too narrow or not.
https://docs.google.com/document/d/1Hj77Ul1V2jl6Ry-4_Em-l9J6g1UPxiqxS0LeSdvlTJM/edit?usp=sharing

What are you thinking of this focusing on, mainly the stack mechanic? Could add a way to add stacks without using a  bite,

Also

Venom Purge: As a bonus action, gain temporary HP equal to Xd4 damage from Kaviss, and burn Stacks equal to X (5ft range); wrote:

how'd Kaviss get here lol

My intent was to focus on the stacks, have it be a tradeoff between consistent damage (the damage at the start of each turn) V.S. burning them to gain additional effects.
And yes, this is Kaviss' subclass, made it myself for him. Only thing that I think i might nerf is the temp-HP, or at least make it work like all other and not let it stack.