Tyrant of Valakut is a perfect example of this mechanic. He usually costs 5RR to cast for nothing more than a 5/4 flyer. But if you are able to cast him for his Surge cost of 3RR, he also deals 3 damage to a target creature or player. He becomes fairly playable.
But the deck has some other goodies, as well.
3 Lavastep Raider
3 Umara Entangler
2 Stormchaser Mage
2 Reckless Bushwhacker
3 Goblin Freerunner
2 Cloud Manta
1 Cyclone Sire
2 Jwar Isle Avenger
1 Windrider Patrol
1 Tyrant of Valakut
Non-Creature Spells (15)
1 Boulder Salvo
1 Ugin's Insight
1 Roiling Waters
1 Rolling Thunder
1 Grip of the Roil
2 Comparative Analysis
2 Containment Membrane
2 Pyromancer's Assault
1 Blighted Gorge
1 Evolving Wilds
For example, the Tyrant has a converted mana cost of 7, but you can cast him for 5. This means Ugin's Insight Scrys for 7. Being able to have more of a choose over the 3 cards you draw is pretty useful. It's an interaction that's not clear on the surface, but it's a pretty decent one.
Grip of the Roil is an okay card as a 2U instant that taps down a creature until the end of your opponent's next turn and draws you a card. It's significantly better, though, for its surge cost of 1U. Comparative Analysis is likewise somewhat mediocre as a 3U instant to draw target player two cards, but at 2U for its Surge cost, it becomes an Instant speed Divination. It's not exciting, but it's a lot more playable.
Containment Membrane is an Enchantment that for 2U is fairly meh. This aura keeps a creature from being unable to untap during its controller's untap step. What makes this one playable is that it has a Surge cost of only a single Blue mana. It suddenly looks fairly good.
While none of these non-creature Surge spells are super exciting, they become slightly more efficient versions of effects that have existed on previous cards. In the Two-Headed Giant format they were originally created for (a format where 4 players play in teams of 2), these are actually really good spells. In an ordinary two-player game of Magic, they still serve as fairly useful cards in a deck that wants to cast multiple spells in a turn.
As Intro Packs go, "Surge of Resistance" is pretty easy to upgrade. There are a lot of unexciting creatures in the deck that can be easily replace. Jori En, Ruin Diver should be at the top of your list and replace the rather inefficient Pyromancer's Assault enchantments. While she doesn't deal damage when you cast your second spell each turn, you get to draw a card instead. In a surge deck, not running out of spells to cast is extremely important. As she's a Legendary, you don't really want to run more than 2 or 3 copies since you can only control one at a time.
Having Haste herself, she's the perfect complement to Stormchaser Mage and any cards with Surge. She also has Prowess, benefiting from the same spells you cast to boost the Mage.
While he lacks Haste, he makes up for it by exiling the top card of your library when he enters the battlefield. You have the choice to cast this cast that turn - or risk losing it forever. But with a deck with alternate Surge casting costs, you'll more often than not be able to cast what you reveal with the Abbot. Be sure to wait to drop your land if you can before casting the Abbot, so you don't just permanently exile a land. This is essentially like drawing a card and fuels the Surge strategy immensely. The Prowess is relevant, too.
We are cutting a lot of Blue spells, but this is okay since we're adding Jori En and a couple more copies of the Stormchaser Mage. In the long run, it evens out.
Which line of play is better in the long-run? What Abbot can reveal can be more inconsistent. Also, the Prowess of the other two can make them more consistently powerful. But both ways can work. Also, having to recast creatures turn after turn can preclude you from playing other spells in addition. But some combination of all these can work if you can't get play-sets of Swiftspear or Abbot altogether at once.