Looming Mystery

This spell casts {1} less to cast for each card in
your hand.
Exile the top ten cards of your library face down.
Sacrifice this permanent: You may look at cards
exiled with Looming Mystery and play one. Exile
the rest face down.
Questions everywhere: Nassian Ven, Ral's project,
Lazav. All they needed for the answers was a spark...