Which units would you like to replace or add?

Instead of Djinns, why not use Ifrits...?
They would definitely fit in... Give them abilities similar to Djinns (Ifrit casts a random curse, Sultan of Ifrits casts a random curse on multiple units for 2 turns).
And add health in exchange for speed.
And replace Gargoyles with... Djinns, but smaller and weaker...