Related to Does Humility stop all creatures from being able to morph?: The question specifies morphs, but I wondered if this was true for Manifest as well? As Manifest is not an ability on the card, does Humility prevent it from being turned face up for its mana cost?
You can still turn a Manifested card face up even if it would lose all abilities from a card like Humility.
This is actually called out explicitly in a ruling on Manifest cards:
Unlike a face-down creature that was cast using the morph ability, a manifested creature may still be turned face up after it loses its abilities if it’s a creature card. (2014-11-24)
This is because the thing that lets you turn a Manifested card face-up is not an ability on the card itself that it would lose. Instead, the thing that lets you turn a Manifested card face-up is the Manifest rules themselves, which just say you can turn it face-up for its mana cost any time you have priority.