Cuba's final card battle requires holding off invulnerable Ysalte while giving enslaved Amayon enough strength to begin casting.
Only crawlers in Cuba may participate in The Big O, while every other surviving crawler watches on dungeon screens. The phase lasts ten minutes.
Ysalte wants to take Amayon into the Ascendency as a hell-prince retainer. Amayon wants to return to Sheol but cannot begin until made strong enough to overcome her control.
Both sides receive decks. Ysalte is invulnerable, so the crawlers must endure rather than kill her. Amayon will refuse to flee until all six of his totems have died.
A ten-minute card arena between a dwarf goddess and giant demon, with Cuba's crawlers caught between them.
The Big O is the immediate battle that decides whether the global rescue continues.