Shell Shield

Shell Shield is a defensive move that Koops can learn in Paper Mario: The Thousand-Year Door upon reaching Super Rank. At the cost of 4 FP, Koops will place a large Koopa Shell over Mario which will take external damage in his stead until the Shell's HP is depleted. The amount of HP the Shell has depends on how well the Action Command is executed: the button must be pressed when the cursor is as close as possible to the center of the gauge. Depending how close the cursor is to the center, the shell will have two, four, six or eight HP. While the shell is up, it will negate all damage to Mario, even if an attack's damage surpasses the shell's HP. The only way to see its HP is to equip the Peekaboo badge, although the cracks on the shell also help indicate how much HP it has left.

Although the shell will protect Mario against all external damage while it is up, Bandits can still steal items from him. Furthermore, the shell is not up during Mario and his partner's attacking phase, and if Mario takes damage during it (from the audience, stage hazards, Bulky Bob-omb detonations or recoil), the shell will have no effect.

This move has an opportunity for a Stylish move by pressing as the shell hits the ground.

There is a glitch in the game that affects this move. If Mario is hit by an attack that does not do damage, either due to Mario's Defense Power negating the damage or the player guarding with the Action Command, the move's Action Command becomes bugged. The Action Command still functions as intended, however, the audience will always react as if the Action Command was missed, resulting in very little SP being restored and audience members leaving. This also causes the "Good!" or "Great!" messages to not show up, even if the Action Command was executed correctly. The glitch is fixed if Mario is hit by a move and takes damage.