@BOBtheBEAR how many maxed 4*/5* healers do you have? Bring them all.
Bring:
5x Harpoons
5x Dragon Attack
5x Bomb Attacks
5x Axe Attacks
Kill the mob waves without spending any items, using many healers is the key.
Throw all Dragon Attacks, Bomb Attacks, and Axe Attacks when the boss wave started.
Throw 2x Harpoons to Santa, 2x Harpoons to Mother North, and 1x Harpoon to Buddy.
Santa & MN should be dead by then while Buddy will be left with small ammount of HP, kill him with your heroes/puzzle.
Do not ever spend gems to use continue.