Neviad, Master of Subterfuge

Hexproof
Whenever Neviad, Master of Subterfuge deals
damage to a player, that player exiles a card from
their hand at random. If that player is hellbent,
they exile the top card of their library instead.
For as long as that card remains exiled, you may
look at it, you may cast it, and you may spend
mana as if it were mana of any type to cast that
spell.(A player is hellbent if they have no cards in
hand.)