This isn't just a prayer. All general spells (like divine power, for example) also don't work. Debuffs also don't work!:D
When a griffin is in the sky, it's invulnerable to magic and any other effects! This is obvious, IMHO.
p.s. Please remember that Armageddon also doesn't work. Isn't that funny? 6 stacks of griffins, they all fly up, and the hero casts Armageddon! :D
