We can use manifest as a jumping-off point, not necessarily as the exact mechanic to go to. Part of the reason manifest worked was because of its combination with morph. If we're using manifest as-is, we'll also want to have morph or a variant thereof. We could use morph, or we could use a riff of manifest that doesn't require facedown cards. Maybe "Reveal the top card of your library. If it's an enchantment, put it onto the battlefield." Or something?

How does people turning into dreams make sense?