His dash attack cannot be blocked. Shield using chracters should guard and attack when you re totally sure you will not receive damage,and the Widzard should attack and use magic whenever he gets on direct fight. The elf has an easy time shooting from safe distance. It will most than likely not attack you,and when the head you were attacking dies another one will come to take it s place and will fall to the same trick. With the fighter and the Cleric,just Guard and attack when you can.
Shield using characters just guard and attack.
Only his dash punch can break your defenses. Ranged attacker just keep jumping to evade rocks and attacking. They key here is speed. Kill it as fast as you can. Shield using characters have an easy time guarding and attacking with caution but ranged characters should have some practice on jumping and attacking,or they will get roasted in no time.