The players are on a lava flow, standing near the bottom of a stone platform with two to four ramp-like slopes. A couple of seconds later, Spike drops on the round top of the platform and spits out a Spiked Ball at the top of each slope.
The players have a short time to pick one of the objects shown on the screen to defend themselves from Spike's Spiked Balls. If players choose a hammer, they will bat the Spiked Ball back at Spike. A regular hammer earns the player one point, but a golden hammer deals more damage to Spike and gives the player three points. If the players end up picking a branch or do not choose anything within the allotted time, the Spiked Ball will flatten their characters, costing them a point.
The number of items varies depending on how many players are present, but during the very first round, there will always be enough hammers for everyone (with only one being golden). As Spike's health drops, however, the number of hammers to choose from will start to decrease, ensuring that at least one player will lose a point per round. In a two-player game, there will always be enough hammers for both players during the first half of the minigame.
When Spike's health reaches its midway point, the rising lava will force the players to move closer to Spike, giving them less time to choose an item. Additionally, the number of hammers to choose from will decrease even further, being reduced to only one hammer in a two-player game and two hammers in a four-player game. In a three-player game, only one hammer is present when Spike has less than a quarter of his health left. As usual, players who deliver the finishing blow to the boss receive three additional points, and the player with the most points after the battle wins.
Spike falls on his back and explodes, revealing Mini Stars in Party Mode and Solo Mode.
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