Once you get the perks butterfingers, loose lines, and slayer, turn on chemical warfare as a relic. It can instantly kill, or take away the weapon or armor of anyone the fart hit, so you can just jump around and watch people in diapers chasing you with swords or knives and then just suddenly die. It's super fun.
The best way I found to kill all bosses is to use archer, upgrade archery and well trained and have your dog attack the boss and you just shoot arrows as fast as you can at it.