The presence of the reborn Forged Existence proved that Heresy could remove its immunity to the sun.
If the Heretic himself was immune to the sun, then there was no hope to begin with. Heresy had that natural counter to all existence in the World, and regeneration on par with the likes of the Origin Hydra.
Just as a feeling of despair was being riddled over some members, Kan'na interjected, "Hold on."
Taking control of the hologram Kan'na returned the projection to show the Northern Continent, "This storm above the continent says otherwise. If the sun was truly not a problem, the Heretic wouldn't need to have a perpetual storm brewing over the entire continent. Moreover the Forged Existence had some pretty specific requirements to be born. If the Heretic could recreate it, I'm willing to bet that it's too expensive to apply it to everything."
