Earthia appeared to Cosmo and told her that only she could save the universe. Cosmo's amulet then shattered and she transformed, helping Super Sonic and Super Shadow defeat Final Mova, an enhanced form of Dark Oak. Eventually, she sacrificed herself and fused with the Dark Oak planet, allowing Miles "Tails" Prower to fire the Sonic Power Cannon, destroying the planet and killing Dark Oak and Cosmo. In the Japanese version, Sonic and Shadow used Chaos Regeneration in order to keep her alive. However, it left behind nothing but a seed. In the dub, Chaos Regeneration is not used and Cosmo implies the seed is her child.