Elden Ring PC | Erdtree Avatar boss fight co-op w/1 summoned player & an uninvited invader on NG

Open-world boss fight like this means no fog gate.

Drops:
4,350 runes
Cerulean Crystal Tear
Ruptured Crystal Tear

Erdtree Avatar
"Erdtree Avatar is a Boss in Elden Ring. This large, headless creature looks like a tree stump wielding a large staff, and is usually found guarding Minor Erdtrees. Most avatars drop materials for improving the Flask of Wondrous Physick. This is an optional boss as players are not required to defeat it to advance in Elden Ring."
https://eldenring.wiki.fextralife.com/Erdtree+Avatar