Hildibrand Manderville

An adventurer card uses only its non-Adventure characteristics in every zone except the stack, as well as while on the stack if not cast as an Adventure. Ignore its alternative characteristics in those cases. For example, while it's in your graveyard, Jidoor, Aristocratic Capital is a colorless Town land card whose mana value is 0. It can't be the target of Sorceress's Schemes, which reads in part "Return target instant or sorcery card from your graveyard or exiled card with flashback you own to your hand."

You must still follow any timing restrictions and permissions for the card you play from exile. In the case of any of the five lands in this release, you'll be able to play it only during your main phase while the stack is empty and only if you have an available land play remaining.

Casting a card as an Adventure isn't casting it for an alternative cost. Effects that allow you to cast a spell for an alternative cost or without paying its mana cost may allow you to apply those to the Adventure.