Lumbering Battlement combo deck - loop infinite ETB triggers by putting 3 Lumbering Battlements (or Mirror Images thereof) into play. Maybe not the best deck in standard, but what a highlight reel when it goes off! 

Check out my article on The Shadow Nexus covering this and other new Azorius archetypes for Ravnica Allegiance: http://www.theshadownexus.com/into-the-arena-the-lumbering-arm-of-the-law/

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NOTE: Since I've been playing this deck in the Magic Content Creator Challenge Cup (with some modifications to comply with its deckbuilding rules) I had to change my tack. The value creature build wasn't working out - Hostage Taker and Deputy of Detention are great tools for a deck that's applying pressure (or protecting them with countermagic), but without a clock they are too vulnerable here.

I felt pretty bad about taking the deck closer to traditional control, since I'd rather not be a strictly worse Teferi or Chromium deck. But I found a build which still makes use of what advantages our combo finishers have while having a more solid suite of tools to protect ourselves and find the 4 cards we need. 

As our combo finisher, Wall of Lost Thoughts is not only more survivable on the battlefield and a viable blocker, it can also provide the card selection we need to ensure our complicated combo kill comes together. Just mill yourself with the EtB trigger until you put a Battlement or Mirror Image in the yard! 4 Memorial to Folly are one means of recursion at 0 deckbuilding cost, and getting to play 4 The Eldest Reborn is even better! Having our combo elements pull double duty as blockers, card selection, lands and premium interaction is what makes the deck worth playing. The Eldest Reborn also helps Mirror Image feel a little better in a build without the extra EtB creatures for it to clone; you can instead copy whatever your opponent's best creature is that your saga managed to reanimate.

Phyrexian Scriptures was chosen for its ability to save one of our creatures from the wrath (since they are also our combo pieces) and for the possible utility of graveyard exiling. I would consider it very much a flex slot, and would not be at all surprised if the correct cards there were Chupacabra (for Mirror Image/Reanimation value) or more Kaya's Wrath.