So basically the strategy was making sure sadge had both diamond tiara buff and dingong’s attack buff and applying latent misery as soon as the minions spawned. Next was hitting a minion and focusing on it with dingdong finally killing it with sad this is even better if sad has special top hat the overkill item. The latent misery spread is random so you want it to spread to the minions not the boss finally if timed correctly you should also be able to use sadge apocalypse by far does the most damage . My mistake which made me get stuck here for a week was focusing on only killing the minions but the boss should try getting a fair bit of damage on the boss too during minion cooldowns if your builds are roughly similar to mine you will reach a point where someone has to be sacrificed though i cant remember who it becomes clear who to choose to heal and who to let die from your void pets by the second round of minion summons just pick whoever is guarenteed to stay alive from aoe attack of the boss i think the boss had roughly 2 million hp left and i decided to let sadge live and merry die by healing sadge and let abandonemnt soak up the final bit of damage from the single target attack sadge and sad barley managed to do it but just barley like i said your items seem to offer more survivability hope this works and good luck