Pain Land Cycle
The Pain lands offer the best gains for two different strategies. Aggressive decks can splash for more fully move into multiple colors without suffering tempo loss to tapped lands. The temples have proven to still be valuable even for aggro decks, but playing to curve is still ultimately plan A. The other decks that will be eyeing pain lands are those that want to push into heavy 3 color requirements and further. There's a lot of power to be found in going multiple colors, you just play the biggest and best spells in the format.
Chord of Calling is really at its best when it's doing one of two things. Either you're searching out combo pieces and the tempo loss of tacking on 3 more mana to the casting cost is made up by just winning the game, or you're using it to go find silver bullets for the match-up. While there are always a few janky combos in Standard, I haven't seen any good ones yet that would make Chord of Calling really viable, so its life in Standard is going to weigh more on the later method. However, I do see it having some success there. Chord of Calling gets to serve as the pseudo-fifth to eighth copy of your important cards and also lets you stack the deck with a few important one-offs, leaving you more space in the sideboard. It's still going to be best in a deck that can generate a lot of mana, but this card can get pretty sick when Nykthos, Shrine to Nyx and Burning-Tree Emissary enter the picture.
A lot of time this card is basically Ruric Thar, The Unbowed and domes your opponent for getting it off the board, but it's a Ruric Thar, The Unbowed that can go in any color deck and has some potential interaction for being an artifact. For instance, Shrapnel Blast + Scuttling Doom Engine is a pretty stupid amount of reach. I'm not convinced there is enough gas to make Standard artifacts a thing quite yet, even Modern Affinity has bad draws and that deck gets to plays with some really powerful cards, but it's not unreasonable. However, this card lines up very well against Elspeth, Sun's Champion.
And finally. Does your deck play Swamps while also playing other lands that don't make Black mana? Like maybe the ever popular Mutavault? If yes, then replace one of those Swamps with a Urborg, Tomb of Yawgmoth and enjoy a slightly better mana base. Done and done. Also, it is worth noting how Urborg, Tomb of Yawgmoth interacts with Mana Confluence. Because Mana Confluence is now a Swamp it can tap for Black mana without losing life.
So those are the cards I think will have the biggest impact this weekend. Are there any that you think I missed? Or what decks do you feel get the biggest boost from M15? I'm hopefully going be at SCG Baltimore Open this weekend and will get to see firsthand what cards have having the biggest effect. Personally, I'm leaning towards sleeving up RW Burn for the weekend. Stoke the Flames is a solid upgrade for the list and folks will be wanting to play with unrefined new decks and stretching their mana further with pain lands. All of which plays right into the hands of just burning your opponent from 20 to 0 quickly.