Recently, the Watchtower live-stream showed an impressive look of Cheetah and Swamp Thing's fighting styles and a more detailed look at Firestorm. The live stream also showed details about what NetherRealm refers to as Source Crystals, which will control the microtransactions economy in Injustice 2. However, the Source Crystals will not be available for purchase to unlock the most powerful gear and the characters. Instead, it is strictly dedicated for cosmetic upgrades and time savers.
Real-world money can be used to purchase Source Crystals, and it can be utilized to buy cosmetic bells and whistles for the player's favorite characters. In addition, this could also be used to buy premium skins which could change the way the heroes and villains will look entirely, and there will be different shades that are available for purchase.
The most interesting application for Source Crystals is its ability to Transform Gear. For example, the perfect helmet for Atrocious can be unlocked; it can fit in with the rest of his armor. It will look exactly like how players want it to be. There is, however, a problem with the stats that are totally wrong for the character build that the player will be going for, according to WWG. Utilizing the Source Crystals can retain the helmet with the stats that will fit the player's play style, while transforming its look that would fit with the rest of the armor.
The Source Crystals will not in any way affect the gameplay or game progression, and NetherRealm does emphasize that these can be used to save time especially when leveling multiple characters. However, it is necessary to remember that the Source Crystals cannot be used to level up the player's favorite characters to level 20 right away; at least one of the player's characters must be already at this level before they can use it to boost other characters.