It is not unlike many of the variable mana cost mechanisms like kicker or level up, all of which are good in the same regard however it has this elegance that the others lack that really gives it aesthetic appeal
If any permanent has an ability that triggers when the permanent you return leaves the battlefield, that ability will be put on the stack after you finish casting the spell, and it will resolve before that spell
Aurora, Regal Princess x3 Aurora, Briar Rose x3 Aurora, Dreaming Guardian x1 Flounder, Voice of Reason x2 Gramma Tala, Storyteller x2 Jasmine, Disguised x2 Maleficent, Sinister Visitor x3 Maleficent, Uninvited x1 Mickey Mouse, Detective x3 Mufasa, King of the Pride Lands x2 Scar, Mastermind x1 Develop Your Brain x3 One Jump Ahead x2 Coconut Basket x3 Magic Golden Flower x2 Beast, Hardheaded x2 Cpatain Hook, Forceful Duelist x3 Goons, Maleficents Underlings x2 Hercules, True Hero x2 Kristoff, Official Ice Master x2 Maui, Demigod x1 Prince Eric, Dashing and Brave x2 Simba, Rightful Heir x2 Simba, Returned King x1 Fire the Cannons x2 Grab Your Sword x1 Ransack x2 Smash x2 Frying Pan x2
It's nasty good here and in many other places
