In Shadow Survival, you will find lots of amazing randomized loot, including Spellstones. They can provide countless possible abilities, such as summoning help to do battle, calling down a lightning storm, a meteor shower, or throwing a god like fireball, etc. The possibilities go on and on, and you can find stronger variants of these abilities as well. Here are a few pictures of how some look in the inventory, and a early look at some in action.
This system, as the others, is going to grow far more diverse in future updates, stay tuned.