It’s the Nozdormu day Quest, and yes, the text is bugged, but anyway, you can complete the quest as usual, playing 3 games with Nozdormu Eternal in your deck:
[7/14 Added] Nozdormu day is back! But there are reports that the text of the daily quest is not appearing for all players. If you receive a “blank” daily, it’s Nozdormu in disguise! The quest can be completed normally: Play 3 games with Nozdormu the Eternal in your starting deck. Have fun out there, Nozdormu fans.