Your opponent cannot target "Palace of the Elemental Lords" you control with card effects, also it cannot be destroyed by card effects. Once per turn: You can Tribute 1 monster; Special Summon 1 "Elementsaber" monster from your Deck with a different original Attribute from that monster's. You can send this face-up card from the field to the GY; discard your entire hand, then add "Elemental Lord" monsters from your GY to your hand, equal to the number of cards discarded.
Palace of the Elemental Lords is a key card of Elementsaber decks. It essentially lets your Elementsaber monsters activate their effects without cost, while also pitching an Elementsaber to the graveyard. It can also provide a significant buff to your monsters when comboed with Elementsabers changing their attribute in the graveyard.
Tributing an Elementsaber monster, which can change its attribute in the graveyard, sets up for Elemental Lord or Invoked summons. This also strengthens Palace of the Elemental Lords’ buff.
Elementsaber Aina can be Special Summoned to revive the tributed Elementsaber.