Along with the special abilities for each character you can also purchase various enhancements to improve your run. They are as follows:
IOS-8 Strength - this protects you from one obstacle or minion. The first level goes for 300 gold, and will last 15 seconds.
Coin Value - this boosts your coin value a certain percentage. To get started with an increase of one percent - yes, one percent - you'll need to spend 300 gold.
Power-Up Duration - this increases the duration of invincibility and Magnet power-ups. It'll cost you 600 coins to start off, doubling your time from .3 seconds to .6. That does make a difference in game though, believe it or not.
Wasp's Wings - this gives you a 390 meter head start on your run, and costs 400 gold. One-time use.
Captain's Shield - this prevents defeat from collision with an obstacle a single time, and costs 200 gold. One-time use.
Doctor Strange's Charm - use this to fill your special attack bar up 50 percent. It's a one-time use for 100 gold.
Protection of Mjolnir - this keeps your special attack bar full as you change back to your SHIELD character. It's a one-time use for 100 gold.
Super Hero's Spirit - this extends your run with your current super hero for 20 seconds, even after you are defeated. It's a one-time use for 300 gold.