Same thing for every boss. The (straight-straight) path can be done by luring all the oakhearts out of the room (one player aggros them all and leads them out of the room, they will no come back, everyone else can stand behind the tree and kill him). The up path requires even less effort, requiring players to just stand behind him and auto-attack him down. The last path (straight-up), is also a joke, as you can see.
Really wish these fights were actually fun. And PLEASE DO NOT just make the mobs aggro everything. No group, no matter how skilled and organized can handle that many mobs (in the case of both the oakhearts and spiders).