I believe Legacy players call this deck "Waterfalls." Regardless of its name, this deck is awesome. Shardless Agent strategies are often midrange decks that end up being well-positioned against other midrange decks. Shardless Sultai attempts to be a little better against combo decks, but Temur Cascade basically ignores them. In a tournament like a StarCityGames Invitational, that is probably a good strategy.
Shardless Agent is probably the best card in the midrange mirrors, so playing Bloodbraid Elf should be an obvious inclusion. This deck can get even go a step further and play something back-breaking in midrange mirrors like Punishing Fire, but Echecetmat35 decided to forego that in favor of the versatile Izzet Charm. The Charm is one of the few counterspells that you don't mind cascading into, plus it pitches to Force of Will. One thing I think these decks overlook is the ability to play Boom // Bust as a way of beating up on control or combo decks.
It can be tough to pull the trigger on playing a deck like this. Having my Thoughtseizes and Hymn to Tourachs makes me feel relatively safe against combo decks. If you don't expect a lot of combo decks, this deck is an excellent choice!