Outrageous Robbery (MKM-BF)

Instant

Target opponent exiles the top X cards of their library face down. You may look at and play those cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any type to cast it.

"When you can't erase your own trail, leave as many false ones as possible." —Etrata