Once per turn (Quick Effect): You can send 1 "Elementsaber" monster from your hand to the GY, then target 1 face-up monster on the field; change it to face-down Defense Position. Once per turn, if this card is in the GY: You can declare 1 Attribute; this card in the GY becomes that Attribute until the end of this turn.
Attribute Changing in the graveyard is usually not impactful.
Elementsaber monsters discard other Elementsaber monsters as cost for their effects. This also loads your graveyard with monsters of different attributes, empowering your Elementsabers with Palace of the Elemental Lords.
Palace of the Elemental Lords pitches Elementsabers to the graveyard in place of their regular cost. Aside from that you also get to search Elementalsabers by giving up your battle phase.
Elemental Lord monsters can only be summoned when a specific number of monsters in the graveyard share a certain attribute. This makes Elementsabers perfect for summoning Elemental Lords because they are able to adjust their attribute while in the graveyard.
Invocation uses cards from your graveyard as materials and depending on the attribute of the monster paired with Aleister, summons an Invoked monster. Elemental Lords can change their attribute in the graveyard to let you Fusion Summon the Invoked monster you need.