If the opponent Kaalia attacked is no longer in the game when its ability resolves, you may put an Angel, Demon, or Dragon creature card onto the battlefield tapped, but it won't be attacking anyone and it won't be an attacking creature
Mind's Desire is a great way for a storm deck to get the final push of cards it needs to close out the game
Its cost is relatively high, but it doesnt require much to equip, its typing interacts with Kaito, Bane of Nightmares, and Dimir Tempo lists currently use plenty of cheap creatures with flying, making it a way to turn any of them into an efficient clock and hand filtering, not to mention potential instant-wins with Dig Through Time and the like
In Commander, this is going to pair very nicely with Foundations Jumpstarts Dionus, Elvish Archdruid to get a second and third untap, especially in High Perfect Morcant decks that are also busy tapping to proliferate counters
Even better, when one of your legends dies, you get to bring back a cheaper one from your graveyard to the field
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