Prior to Scars of Mirrodinthere was only a single Locus in the entire game of Magic: Cloudpost (okay, and Vesuva if you wanted to copy it). With the printing of Glimmerpost in the return to the plane of Mirrodin, deckbuilders were gifted a second playset of Locuses and, alongside the aforementioned Vesuva, could play up to twelve in one deck. Each copy would increase the amount of mana generated by Cloudpost (and any Vesuvas copying Cloudpost) and the world was ready for such a deck to take over provided there was a format for it.
No one missed the memo on the interaction between Cloudpost, Glimmerpost, and Vesuva, and the archetype it spawned (Twelvepost) is one of the most popular here at Magic Weekend Philadelphia. What many players fail to realize, however, is that the more popular Locus decks are, the harder it is to play them. Why's that? Because of one simple line of text on the original Cloudpost:
"...for each Locus on the battlefield." (Emphasis mine.)
Cloudpost counts the total number of Loci on both sides of the battlefield, meaning each one your opponent has makes yours more powerful, and vice versa. This makes playing the mirror match tricky, and has changed how players interact with one another and the battlefield. But just how exactly has it impacted play? I set off to find out by asking some of the big names playing the archetype here in Philadelphia.
I ran into Travis Woo, fresh off a deck tech over in the video area of the tournament halls, and asked him if it was something he had worried about on the weekend. "It definitely comes up," he answered. "It means sometimes you use Vesuva to copy a basic land, actually." That interaction is particularly important to remember if you need mana; just because Vesuvacan copy a fancy nonbasic land doesn't mean it's the best play for it to do so.
"You want to play Glimmerpost as your last land a lot," Travis continued. By playing it last, he pointed out, you're less likely to pump up an opponent's mana count for Cloudpost. "Also, you have to hold cards like Beast Within," Woo continued. When I pressed him as to why, he clarified by saying, "If their Cloudposts allow you to cast an Emrakul or Titan a turn earlier, you'd rather keep them on the table."
Travis jogged off after that to give his Limited deck some test runs, but I promptly spotted Belgian star Christophe Gregoir, who was also playing Twelvepost. I pressed him with the same questions, and he added to the thought process behind the mirror. "You always have to be aware of the mana count," the European star pointed out. "Every time you cast Primeval Titan you have to consider whether you're going to help them untap and cast Emrakul," he explained, calling out Emrakul, the Aeons Torn by name. The infamous Eldrazi is the keynote spell in the deck, the exclamation point at the end of the giant mana ramp.
Are their versions of the deck that have been built with the mirror in mind? "I played against the green-white version with Scapeshift and Summer Bloom," he replied. How did those cards help in the mirror? "They use Summer Bloom to play Selesnya Sanctuary and bounce all of their Cloudposts to prevent you from benefitting from any of their mana," he explained—a clever play that kept the Locus interaction in mind even during deckbuilding.
"Sometimes the mirror comes down to both players having a lot of mana, but not having drawn an Emrakul," Christophe pointed out, adding, "Then it's about Eye of Ugin. You really have to have that enter the battlefield untapped so it's not destroyed by theirs or a Vesuva. Sometimes when I attack with Primeval Titan I'll hunt it up with Gruul Turf so I can bounce [Eye of Ugin], play it after combat, and use it right away."
None of the players I talked with had experienced a situation in which their opponents didn't realize how the Loci interacted with one another, but it's entirely possible that amongst the field of almost five hundred players, someone did. Will you? Hopefully not after reading Travis and Christophe weighing in on the matter!