Ok Im not sure if Im allow to do this combo since im not too well verse in the new rules, but it only involves three cards.
1.Magician of Faith
2.Book of the Moon
3.Magical Citadel Of Endymion
So I play my Magician of Faith in attack mode, then I play my Magical Citadel Of Endymion field card, and finally I play my Book of the Moon to put my magician face down. Am I allow to flip it back face up after my spell card put it face down? If so. then I can use Magician of Faiths effect to bring back my Book of The moon and then play it again to put Magician of Faith face down again and repeat the process infinitly, why? That where Magical Citadel Of Endymion comes in which gains a counter everytime a spell card activated and there's no limit to how many I can place on this card, it also has the effect of removing one spell counter to save it self from being destroyed, and once per trun can use its own spell counter to pay for the cost other cards that need to remove spell counter to activate their effects. This combo alone makes Magical Citadel Of Endymion indestructable but what makes it even more deadlier is that I can remove six counters from it to special summon Endymion, the Master Magician from my hand or grave yard, this lets me bring him back every turn if he gets destroyed and by summoning him this way I allow to retrieve a spell card from my graveyard. He also has the effect that can destroy a card on the field be discarding one spell card. As you can see this is very devestating combo that might even get Magical Citadel of Endymion banned, but only if I can flip my Magician of Faith back up from Book of the Moons effect of putting it face down, so the question is can I flip Magician of Faith back up after using a spell card to put it face down and repeat the process?