Doomfall

Choose one —
• Target opponent exiles a creature they control.
• Target opponent reveals their hand. You choose a nonland card from it. Exile that card.

Amonkhet Remastered

"This place has outlived its usefulness."
—Nicol Bolas

Hour of Devastation

Choose one —
• Target opponent exiles a creature he or she controls.
• Target opponent reveals his or her hand. You choose a nonland card from it. Exile that card.

If you choose Doomfall’s first mode, the target opponent chooses which creature to exile. That creature isn’t targeted, so a creature with hexproof can be exiled this way.

If you choose Doomfall’s second mode, you must exile a nonland card from that player’s hand if able. If you can’t, most likely because that player’s hand contains only land cards, nothing happens. That player won’t exile a creature they control instead.