Zalur's Messenger

When Zalur's Messenger enters the battlefield,
choose one:
• Each player reveals the top card of their library,
loses life equal to that card’s converted mana cost,
then puts it into their hand.
• Each player returns up to one target nonland
card from their graveyard to their hand and loses
life equal to that cards CMC.
Which haunts you; the unknown or the unforgotten?
-Zalur, Dream Sequesterer