Ruin Illuminator

As long as you've completed a dungeon, spells
you cast from exile cost {1} less to cast.
{2}{r}, {t}: Choose one —
• Venture into the dungeon. (Enter the first room
or advance to the next room.)
• Exile the top card of your library. You may
play that card this turn.
"I don't have darkvision, and I don't need it."