I don't imagine you'll be doing this very often, but maybe you're out of Lessons, so you planned to discard, but some things happened in response, and one thing led to another, and now it's time to learn, but you have an empty hand, and this is all very embarrassing, and let's just not speak of it again, okay
Flying, first strike Whenever Sidar Jabari deals combat damage to a player, return target Knight creature card from your graveyard to the battlefield
Overall, Delirium is one of my favorite Magic mechanics of all time, and it's one that I welcome in any Limited or Constructed environment
Note: Some card effects like mass land destruction spells, would have dominated the list
In many decks, Dawn of Hope's other ability is just a bonus, and those decks might hardly even bother with it until they need a mana sink later in the game