Beyond the Impossible: Unlike the Vassal Heroes, the Four Cardinal Heroes are incapable of invading other worlds. As her last act, Ost makes it so that Naofumi has "special permission."
The Cavalry: When the Spirit Tortoise revives and starts attacking the army, in comes Fitoria to fight it back on equal footing.
Crystal Prison: We see that Kyo had imprisoned the Three Heroes in one of these within the Spirit Tortoise' deepest depths.
Dirty Coward: Rishia calls Kyo one, pointing out that he only ever uses other people's powers and attacks, comparing his fixation to proving himself powerful to an animal puffing out its fur. The fact that he visibly flinches when she pulls her sword on him just proves it.
Fighting from the Inside: Apparently, the Spirit Tortoise itself had freed Ost Horai from her duties so that she could help kill him.
Infinity +1 Sword: When Naofumi's Rage Shield proves useless with his hatred run dry, Ost activates the Spirit Tortoise Heart Shield, which she then uses to destroy the Spirit Tortoise Core.
Ki Manipulation: Rishia manages to counterattack Kyo's gravity magic by regulated the ki in her body.
Let's Get Dangerous!: The normally meek Rishia finds her nerve and counteracts Kyo's gravity magic holding them all to the floor using Ki Manipulation, beats him in combat and shatters the Crystal Prison the Three Heroes are kept in, giving the rest of her party a chance to get away and regroup.
Power Copying: Apparently the Vassal Book has this ability, as Kyo was able to copy many of the Spirit Tortoise's magic attacks and abilities.
Powered by a Forsaken Child: Kyo had refitted the Cardinal Sword, Spear and Bow as power sources for the Spirit Tortoise by keeping Ren, Motoyasu and Itsuki in a Crystal Prison, turning them into Living Batteries. And the experience seems quite painful for them, too.
Reduced to Dust: When Ost and the Spirit Tortoise die, they dissolve into golden particles.
World-Healing Wave: The particles that the Spirit Tortoise dissolve into turn the barren canyon into a lush plain.
