Excalibur, Sword of Eden

This spell costs {x} less to cast, where {x} is the total mana value of historic permanents you control. (Artifacts, legendaries, and Sagas are historic.)

Equipped creature gets +10/+0 and has vigilance.

Equip legendary creature {2}

"This shining sword itself is the nostalgic, sorrowful, and exalted dream of all warriors past, present and future who stand at the brink of death on the battlefield – the crystallization of the prayer named 'glory'."