Part 52

Phase 1: Bowser has 75 HP. He will summon minions, but focus attacks on Bowser. Recommended stickers include Thing stickers, Flashy/Shiny Shells, or Flashy Fire/Ice Flowers. Using the Thumbtack Thing early can pin doors shut, simplifying the phase.

Phase 2: Defeat the Thwomp to damage Bowser. Bowser has approximately 225 HP remaining. To defeat the Thwomp: use the Eekhammer to knock it over, then use Scissors, OR use a Flashy Infinijump (deals 100 damage, Thwomp has 50 HP). After the Thwomp is defeated, reduce Bowser's HP without using your strongest stickers.

Phase 3: Walls lower, creating a lava pit. Bowser will heal. Lava bubbles appear; freeze them with A/C, Shaved Ice, or Refrigerator to prevent Bowser's attacks. Bring Bowser down to about 175 HP. The Fan Thing can blow away lava bubbles. If lava melts, refreezing is not critical as its attack deals only 16 HP damage.

Phase 4: If you have the Shiny Tail Thing, use it. Let the Chomp hit you, then use the Tail to push Bowser over the edge, advancing to the final phase. Without the Tail, use Slaphammers.

Phase 5: Bowser appears at the edge. Initially, focus on healing and surviving until Kersti joins. Attacks will only deal 1 HP damage. Bowser's slap attack can be halved by pressing A just before impact. Once Kersti joins, use her abilities.