From the Super Mario Wiki
Strong Slammer is a type of Slammer in Luigi's Mansion: Dark Moon powered up by a special crystal. Strong Slammers have 150 HP. They can take down 20 hearts every hit. They usually come alone but when there is two, the player needs to catch both of them by charging the Strobulb longer. Their average weight is 28w. They break out of the crystal by punching the crystal with both arms, almost completely smashing the crystal. The sub-boss from the Secret Mine has 250 HP, and is covered in paranormal chains.
Ghost Container Description
Whoever strengthened these bullies by putting them into the crystals had only one thing in mind: creating ghosts strong enough to crush rocks into dust with a single blow.
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