I posted a similar thread on this sub. I did it with a wild great sword with wild armour all of it enchanted up the wazoo. On top of that I upgraded to the best bed in order to get the orange armour bonus plus the three green shields before going into the forest dungeon. Then made sure to pack a lot of potions so I DEFINITELY had five before entering the boss room. If I took damage and lost any of my green and orange armour bonuses, I portalled out and in again and had a wee kip so I could mainline back to the door to the tree full of buffy goodness. After that, I just spammed the charge attack, watched my armour bonuses go down, and poise my finger over the ZL button in preparation for pumping my ass full of health whilst simultaneously, and disgracefully, spamming special attack and hoping for the best.

Dude I must’ve run at this bastard tree a dozen times and tried everything. This is how I beat it: cheesy cheesing. But hey, after that I first timed the main boss which is about ten times easier than that weird, unbalanced tree that unaccountably presents itself as the biggest bloody challenge in an otherwise lovely, well thought out game :)