Venomous Valour is a Side Quest in Hogwarts Legacy. This walkthrough will guide you through all objectives of the Venomous Valour side mission.
Location: The Astronomy Wing -> Defence Against the Dark Art Tower
Quest Giver: Duncan Hobbhouse
Quest Level: Level 5
Requirement: Having Finished Professor Hecat’s Assignment 1
Reward: Appearances, 180XP
Mission Info: Duncan Hobbhouse seems to have a Puffskein problem. I wonder If I can help him out.
Objectives:
- Talk to Duncan Hobbhouse
- Find and enter the Hidden Herbology Corridor
- Obtain Proof for Duncan
- Collect Giant Venomous Tentacula Leaf
- Return to Duncan
Starting Location: Venomous Valour
Talk to Duncan Hobbhouse
Talk to Duncan on the ground floor of the Defence Against the Dark Art Tower.
Find and enter the Hidden Herbology Corridor
Follow the Quest Marker to the Hogwarts Grounds, and use Incendio to enter the Hidden Herbology Corridor.
Obtain Proof for Duncan
Inside the Corridor use Lumos to protect yourself from the Devil’s Snare. After a while you will come across this place.
The Proof for Duncan is to the left, but there’s a chest to the right behind the debris with Sleek Duelling Gloves (Legendary) inside. To get there just destroy the debris with 
/ 
.
Now follow the quest marker to find the Giant Venomous Leaf.
Collect Giant Venomous Tentacula Leaf
Just interact with the Leaf.
Return to Duncan
You can now return to Duncan in the Defence Against the Dark Art Tower.
This finishes Venomous Valour Side Quest in Hogwarts Legacy.
For all other Side Quests and Main Quests, check out the complete Hogwarts Legacy Walkthrough.
You missed the chest in the room with a bunch of venomous tentacula. At the back there’s a big chest.
They didn’t count for the objective so I left it out.