As a follower of Zehir you relish in seeking and killing many foes to appease your god and receive his blessings. 

Fangs of the Viper God

When wielding Daggers in both hands, you gain a few benefits.

You may use sneak attack even if you do not have advantage.

Also, as an action you may perform a Serpant Strike. This is an attack that strikes with both daggers as 1 attack. This attack adds all modifiers for both daggers into 1 attack roll adding your dexterity only 1 time. For damage you add all modifiers, and magical effects into 1 roll and add your dexterity twice (once for each dagger) When you use serpent strike you may coat 1 weapon as part of the attack using one of your poisons. Creatures hit by this attack have disadvantage on saving throws vs poison until the end of your next turn.

If you use Serpant Strike you may not use your bonus action to attack with your offhand.

Blessings of the Venom God

You carry around a special idol that bestows several blessings to you.

-Poisons you administer have their DC changed to (8+your proficiency+dexterity) if you are using daggers, you may increase the DC by the magic bonus of your daggers to a maximum of +3

-You also treat creatures with immunity to poison as if they had resistance instead.

-Once per long rest you may have the idol secrete 2 random poisons. Once from each fang.The poisons only work for you, and do not have a gold value, select 2 random from a list of contact and injury poisons only, and exclude purple wurm poison.

At level 7 purple wurm poison has a chance to be received from the idol. 

Serpentine movement

You are fast and slippery to pin down.

Increase your walking speed by 10 feet.

When you use uncanny dodge or evasion, you may move up to half your speed without provoking attacks of opportunity.

Rapid Strikes

A natural and seasoned predator, you attack quickly and precisely. When you take the serpent strike action, you may attack 2 times using the serpent strike attack.

Chosen

Through faithful worship of Zehir, and killing many in his name, you have received his final blessing.

You shed your old skin, and it is replaced with new skin that is slick and scaly, your tongue splits in 2 and becomes forked, and your eyes turn yellow and the pupil stretches into a vertical thin slit.

With your new skin you are able to move better than ever before, increase your dexterity and it's maximum by 2.

Once per short rest, you may temporarily blind yourself as a bonus action, but gain a blind sight of 60 feet. This lasts for one hour or until you use a bonus action to end it.

Your physical appearance is very off-putting to non-believers. When interacting with them, you have disadvantage on persuasion and deception rolls.