Maze's End, on a relatively small budget (compared to other Standard decks).
It's pretty fun! I run a couple other cards that aren't usually in Maze's End, namely Prophetic Prism and Steam Augury. Both are really helpful - Prophetic Prism is great at smoothing out mana and (if you're like me) saving your ass when you forget to leave up green mana for a Fog, while Steam Augury burns through your deck and gives you lots of fuel.
I run two Crackling Perimeters maindeck, mostly because I've often won Game 1's piggybacking on Crackling Perimeter when Maze's End was too slow; occasionally it slows me down when I draw my second one or when I need a fog or a draw spell, but it's not too much of an issue, honestly.
Like every Maze's End deck, the hard part of the deck is stabilizing long enough until you hit a boardwipe. Since I'm poor and I can't afford too many Supreme Verdicts (price-wise), it's a bit harder to draw a Supreme Verdict early on, but the additional cantrips and Steam Augury help a bit during late-game.
You generally want to keep a hand of a couple gates (+at least 1 green/white source OR a Prophetic Prism), and a couple Fogs. Verdicts, Merciless Evictions, Steam Augury/Urban Evolution are icing on the cake and help ensure that you won't have very many dead draws, while allowing you to save your Fogs up for when you need it.
Steam Augury is best used either A. After a verdict, or B. Late-game when you run out of fogs to keep you alive against a full board. There are a couple of risks when flipping Steam Augury, detailed as follows:
1. You flip 4 lands + something else >> Ideally, separate the piles so that you want that "something else", unless you need those 4 lands.
2. You flip two of a non-Simic/Selesnya guildgate >> Separate the piles so that one gate is in each pile, so you can actually win.
3. You flip one of a gate you don't have yet >> Don't play another Steam Augury unless you absolutely need to (to find a Maze's End), until you have that gate in your hand or on the field. Generally this doesn't happen as I usually get Maze's End before the second Steam Augury.
4. You flip a bunch of Fogs, and a Verdict/Eviction that you need: 4 Fogs or 1 Verdict? This shouldn't be an issue. Both are great for you. Hell, you can even go 3 Fogs or 1 Verdict + Fog.
For sideboarding, it really depends on the matchup:
MONO RED DEVOTION/RDW/BOROS VARIANTS has a lot of burn, so if you win game 1, you want to board in some Negates or Swan Songs. Take out the Urban Evolutions and the Crackling Perimeter, as well as some other stuff you don't think you'll need. Against the Boros variant, be sure not to Verdict into a Boros Charm, as that will be game over right there.
BOROS BURN pretty much is our worst matchup, and it's amazing how much there is locally here. The main thing to do is just to side out all of our non-Riot Control fogs and add in more counterspells. I'm thinking about running some Saruli Gatekeepers or Heroes' Reunion for this very matchup. Don't forget about siding in Bow of Nylea as well.
AZORIUS/ESPER CONTROL board in a couple counterspells, but they really aren't that much of an issue unless (against Esper) they have Ashiok - if so, it's best to get some Pithing Needles and Negates/Swan Songs to counter their mill. If they have Jace, Bow of Nylea can slow down the clock on him.
BLACK DEVOTION By far, IMO, the most frustrating matchup. Their Gray Merchants are the main problem, but their Underworld Connections help them get there. Revoke Existence on their Underworld Connections/Whip to prevent them from building up too much devotion, and keep their board clear with Eviction and Verdict. Pithing Needle helps stop Pack Rat and Mutavault as well.
GW AGGRO/MIDRANGE They really don't have much against you - just be sure not to Verdict into a trap.
GR MONSTERS They can get really big really quick, and Garruk/Xenagos are brutal when gotten out early. Game 2 they'll probably side in a bit more burn, so be careful in letting their dudes through.