A monkey boss? What you mean?
It depends what version of him you are fighting, lvl5 or lvl15?
And what Avatar/Class are you playing with?
Each Avatar has a skill that allows the player to defend against his biggest attack.
The best tip I can give you without spoiling too much is to look at your Skills, there is some that are very helpful in that battle. It depends in which part are you having problems. If you want me to be more specific and tell more specific tips, then please ask in the Spoiler topic here: https://dmquetzalli.itch.io/delve-into-pawssion/devlog/382260/guides-and-secrets...