Grasspaw

Spoilers ahead!

Grasspaw is an NPC that can be found in the Apprentices' Den.

After Level 1
The protagonist can sell their crafting items to Grasspaw for 125 Gems each.

After Level 4
The protagonist may sell their items as before, but each item now sells for 300 Gems each. Grasspaw will remark that the price increase was due to assistance received from Shadowfeather.

After Level 10
Grasspaw is in despair after the death of Duskpaw in the BoulderClan attack. He is unable to talk to the protagonist, and they will no longer be able to sell crafting items.