Other than making some potions for healing and stamina (and poison resistance for the swamp later), you are ready.
Btw you can kill him much faster in melee than ranged, just block his stomp, move away from or kill the roots he occasionally summons and that's it. Only bother hiding behind a pillar if you get low on health and your healing potion is on cooldown.
Other than that, just get rested, clear the area from any enemies before summoning him and start the fight during morning.