Just a thought on new, upcoming Troops.
Maybe it’s been up for discussion before, but a nice way to get variety could be to make skills more powerful if there are many gems of a certain color on the board. Like Queen Mab; if there are more than 10 blue you get an extra turn.
Troop X - heal an ally and give barrier. If there are more than 10 (green) gems, heal another random ally, if there are more than 15 (green) gems, heal random ally + give barrier.
This gives much room for experimentation, balance and variety in how the skills work.