Wolcen: Lords of Mayhem – Immortal Final Boss Guide

Untick the Show Damage and Show Critical Damage settings.

If the final boss of the main story decides to inconvenience you by becoming permanently immune to all damage (for me this happened at the start of phase 2 of the fight), please try the following steps:

• press Escape and click Return to Main Menu
• click the cog wheel (bottom right)
• click Settings
• click Gameplay Settings
• untick Show Critical Damage and Show Damage (see screenshot below)
• click Apply and Accept
• select your character and click Play
• restart the boss encounter (you can fast travel by pressing M and clicking the top node)

I do not understand why this works, but it worked for me, and I hope it works for you. GLHF! ^_^