Living End will be stuck face-down in exile. It can't be suspended because the Suspend ability only works from the hand, and it can't be cast with foretell because Dream Devourer 's ability gave it a nonexistent/empty foretell cost that can't be paid. If we use an example with a mana cost, like Search for Tomorrow , it can be cast but not suspended.
May 31, 2021 6:22 p.m. Edited.
I believe you can't activate Dream Devourer 's ability in the first place. Each card in your hand gains a Foretell cost equal to its mana cost minus , notably not its Mana Value (Converted Mana Cost) minus . Living End does not have a mana cost.
May 31, 2021 9:01 p.m.
Yesterday: You can put Living End into exile face-down with the "During your turn, you may pay ..." part of the Foretell ability given by Dream Devourer, you just won't be able to cast it later.
June 1, 2021 9:58 a.m.
Right, yeah. Because the initial foretell cost is always 2, and the cost to cast it from foretell is the part that's based on the card's mana cost. MB.