u/Furfito

Hello,
I have a group of 5 players level 4 that will reach King Grol soon. They will fight him in an open arena outside the castle with his Dire Wolf Snarl (30 PV). My King Grol is a super athletic guy mixing Bugbear Tracker (DND 2024) and Barbarian Rage for phase 2. The group of PC will be well rest before the encounter.
The purpose of this fight is to force PC to use shove and evasion to avoid the use of "Human Shield" reaction.
Do you have any tips and balances ? Thanks