very cool idea.
no reason in my mind that this same mechanic couldn't be applied to physical "special abilities" as well
- a power-up attack that does double damage (useful against high defense)
- a "quick strike"/"intense focus"/"stone skin" mechanism where you meditate for a turn which ups your speed/accuracy/resitance the next.
- a "wall" mechanism where units take damage in the next turn as they move past your unit
and non-magic units could combine their efforts as well:
- a "protect" command, where a unit gives up its turn but it partially absorbs and counterattacks any attacks against the unit its protecting
- a "flank" command, where two units attack as one, with the flanking units attacks facing a reduced defense
- a "back-to-back" command, where if a unit is out of counter-attacks it's partner counterattacks for it (as long as the partner has counterattacks)