G/W Hexproof is one of those Modern decks that people love to hate. There is something about watching your opponent stacking auras on a 1/1 and attacking you with a 12/12 lifelink, first strike, trample, protection from creatures, rampage 3, bands with Arnold Schwarzenegger monster that can make you feel rather helpless.
But G/W Hexproof, the traditional list, is not without its weaknesses. Being all-in on a single strategy will always leave you vulnerable in a format as large as Modern, and Edict effects are certainly an issue you have to deal with when growing your Slippery Bogle to gargantuan proportions. The G/W deck can also be high-variance in its draws, since you need a lot of pieces and you need to assemble them early on. In Modern, if you stumble, you will at best fall far behind and at worst lose the game on the spot.
Typically even the most linear of decks will incorporate a minimum amount of interaction so as to effectively be able to win some of these games while not interfering with its core strategy that much, but the options available to G/W Hexproof to do this are rather poor.
Enter everyone's favorite color: blue.
Since Slippery Bogle costs Simic hybrid mana, it slots into the deck easily enough, but Gladecover Scout has to be cut. Fortunately, blue gives you access to Invisible Stalker, which costs an extra mana but gives you the important bonus of already being unblockable, so you can focus on making it big and giving it lifelink to prevent losing a potential race. To help compensate for the lost speed, we see former Standard all-star Geist of Saint Traft, which attacks for six at a time and will often get in a minimum of four as your opponent focuses on removing the Geist from the battlefield, ignoring its first Angel token.
In this way, Geist combines well with Umbras, allowing you to attack with your Geist into a larger creature for four damage and then do it again next turn, morphing into an eight-damage burn spell. Given that the threat of Geist often forces your opponent to play defense, this eight damage will allow your Invisible Stalker to close out the game rather easily, even if it does not get quite as big as it would in G/W.
The other appeals to going blue with the deck are getting velocity and interaction. For the former we see two copies of Serum Visions, a seemingly insignificant number, but keep in mind we are only trying to move the needle slightly from G/W, which is already a competitive deck. You know the old adage: if it ain't broke, don't fix it. Well, this is more like "if it's only slightly broken, only slightly fix it." We're not trying to reinvent the wheel here, just smooth out the edges to make the ride less bumpy.
Two copies of Curiosity supplement the Visions, but by pulling double-duty as an aura for Daybreak Cornet and Ethereal Armor, they let you develop your aggressive gameplan while you dig for any missing pieces.
The second advantage, interaction, comes in the form of counterspells. Three maindeck copies of Mana Leak and two sideboard copies of Negate give this deck some ability to stop opposing combo decks from racing once you have made a large creature, and the increased land count of the deck allows you to advance your battlefield while holding mana up for these counterspells so they do not require stifling your own development too often. The added velocity of the deck also plays into this by letting you ensure more land drops and find your disparate pieces in the right numbers to operate efficiently.
Putting auras on hexproof creatures may not be glamorous, but it is a proven way to win in Modern, and this twist on the archetype lets you do it with a little more style.