One of the most fun decks to play in Standard has to be UR/Grixis Prowess. It is fast, powerful, and flashy—but not necessarily the most consistent.
Stormchaser Mage and Monastery Swiftspear are among the biggest and cheapest haste creatures to ever come out of the printing press over at Wizards of the Coast. Elusive Spellfist does its best prowess imitation with the huge added bonus of becoming unblockable.
In order to improve the consistency, you need card drawing. Abbot of Keral Keep is a great start, although there is no guarantee that you get even a single relevant card off of the exile. Slip Through Space is an awesome way to force through a big creature and continue to improve consistency with an extra card.
Filling up the graveyard with Slips is a great place to start to fuel delve cards, and Treasure Cruise is the best of the bunch. To add even more fuel to the fire, Magmatic Insight turns delve on quickly while also churning excess lands into potentially more useful action. Triggering prowess for each of these spells is a further bonus.
With more card draw and consistency, you can cut down on combo elements that could be dead draws. Titan’s Strength is always good and the scry only helps your cause.
The final piece of the tempo-plus-card-draw puzzle could be Grip of the Roil. The ability to turn off a blocker for several turns and draw a card for often only 2 mana is pretty sweet. With so many 1-mana spells, the surge will almost always be active!