Dont worry, you will find use for them at some point in the future. Maybe you should just think about laying down the Summon Hammer for a while and focus on leveling and stocking up gold (like 2 million) slowly, cause yeah... black units take a fuck ton to level up. Stacking gold cause of awakening (which costs a lot) and base summon (2k daily) for silver fodders to cc and later awaken. Especialy archers... geez archers...
You can spend those SC to farm Event Maps that got silvers u need to cc or awaken, to get more DC for Awaken or cost reducing Spica. Or to max out an Event unit. Lots of uses :/