With each attack, you get to exile the top four cards of your deck and letting you cast them for free this turn so long as they are noncreature spells
Once the activated ability resolves, the blocking requirement is set, even if the second target creature loses its power and toughness sticker before blockers are declared
At the beginning of your upkeep, if there are five colors among permanents you control, there are six or more card types among permanents you control and/or cards in your graveyard, and your life total is greater than or equal to your starting life total, you win the game
As with so many mechanics on this list, Devotion creates novel incentives out of familiar components
So, the fact you can play it face down first and then turn it face up - without losing that life, is pretty nice
Combined with Ravenous Intruders free sacrifice, its easy to imagine a scenario where this can come down turn 3 and cover either a fallen Intruder or whatever it sacrificed