Get Snakes and Snakes & Beating the Beetles quests from Master Hunter Jillare. Get Exploring Shard's Landing from Explorer Dent.
Killing a slatescale or ivyscale slitherer gives slitherer venom, then killing a venomshell pest gives venomshell spittle, which automatically combine to make an analytic potion.
The potions are then used to gather samples from various beasts in Shard's Landing in the Exploring Shard's Landing quest, doing so automatically if you have the analytic potion in inventory.
You will need 9 potions to complete the samples needed for Exploring Shard's Landing. Once you have them, get the balance of kill quests from Master Hunter Jillare and collect your samples to complete Exploring Shard's Landing.