Knights of the Zodiac, Volume 21 — Masami Kurumada

Seiya and his friends have often put their lives on the line to defend humanity and the goddess Athena. But when the deathless army of Hades invades the mortal world, mere human life may not be enough to stop it. To survive the Battle of the Gods, Athena's Knights will need the power of Heaven itself...

That power is embodied in Shaka, the Gold Knight who draws his strength from Buddhism. Beneath a pair of sala trees, where the Buddha died, Shaka makes his last stand against the Specters of Hades. He's prepared to sacrifice everything and face the Gold Knights' most terrifying forbidden technique. What he learns will change the course of battle...and Knighthood...forever!