I am not super familiar with the power level of Modern Masters 2015 Sealed Decks yet, but this pool looks weak to me. There’s no removal, no bombs, and it isn’t fast enough to beat anyone who has powerful cards. There’s plenty of fixing to splash whatever you want, with four bouncelands, Evolving Wilds, and Baubles, but there’s not a single card worth splashing.
You’re clearly going to play white, as it has some of your best cards like Spectral Procession and Battlegrace Angel as well as some role-players like Blinding Souleater (which can be played without white but is better if you have access to white mana). After white, though, there’s no color that I really want to play. Red and black both have one removal spell each, and RG also has one.
In the end, I opted for black because it had three Sickle Rippers and two Daggerclaw Imps. The Rippers aren’t that big an upgrade over Kami of Ancient Law or whatever 2-drop you’d get in other colors, but Imps are at least a way to win the game. Creakwood Liege is quite good, but hard to cast—you will have 2 Selesnya Sanctuaries as semi-fixers for that, though. Midnight Banshee is not great in your deck since it kills all the white creatures, but it’s still going to be a decent card.
The other option would be WRg, splashing for Vengeful Rebirth. I think the red creatures are worse than the black creatures though, so I lean toward black here. If my opponent had a lot of x/1 creatures, then I’d board into red to use the two Wrap in Flames.