All creatures lose indestructible until end of turn. Hour of Devastation deals 5 damage to each creature and each non-Bolas planeswalker.
7/14/2017 Creatures with indestructible that enter the battlefield after Hour of Devastation resolves will still have indestructible.
7/14/2017 Once Hour of Devastation begins to resolve, no player may take actions until it’s done. Notably, players can’t try to give a creature indestructible again to save it from the damage.
1/19/2018 There are many important moments in the story, but the most crucial—called “story spotlights”—are shown on cards. These cards have the Planeswalker symbol in their text box; this symbol has no effect on gameplay. You can read more about these events in the official Magic fiction at http://www.mtgstory.com.