Dark spells

At th8 or th9, there should be dark elixir spells that may have relation to hero abilities like an invisibility spell for a certain region that lasts for same time as rage spell, range of jump spell and costs 2-5k de.
Also, there should be an iron fist like spell that follows the troops some way like the iron fist ability does with a barb king. So ifnyou drop it on a drag, the spell follows tge drag for a period of time. Skeleton spells may also helpful.*spawning a certain amount of skeletons per second*