The cards you exile from your hand are exiled face up.
The converted mana cost of a split card, such as a card with aftermath from the Amonkhet block, is based on the combined mana cost of its two halves. A split card doesn’t have two converted mana costs.
If a card in exile has in its mana cost, X is considered to be 0.
If an object has no mana cost, its converted mana cost is 0. A converted mana cost of 0 can still help unlock Azor’s Gateway.