My advice is simple.
Viper/Veli/Red Mountain/ Tremorscale/ Widowmaker/ Infernal Guardian/ Grothdarr/ Selene combine the same problematical things a high proc chance with insane damage or debuffs.
So why don't change that proc chance/damage in Cyrodiil only?
It would be something like:
Viper: Your melee attacks deal 8k additional poison damage. While in Cyrodiil the chance is reduced to 4%. This effect has a cooldown of 4 seconds
This would make it harder to stack burst by a huge amount. From 1(viper)*0.2(velidreth)*0.2(widowmaker + poison) ( number of attacks) to a much lower probability like 0.05*0.05*0.2*0.3(widowmaker proc) on procing at a single attack this would reduce planned burst very well