Simplify the following text for a Grade 12 native English-speaking person.
Original: Salamandastron , Mountain of the Fire Lizard , ruled by Badger lord Urthstripe the Strong , guarded by 40 hares of the Long Patrol , is under siege by the weasel Ferahgo the Assassin , his son Klitch , and his army of Corpse-Makers ( vermin ) .
Simplified: Ferahgo the Assassin , a terrible weasel warlord , and his son Klitch lead their army of Corpsemakers to Salamandastron , to take over from the Badger Lord , Urthstripe the Strong .