- Magic in Heroes 3

Blindness is cured with Healing (a play on words:)), and the best way to counter Haste is with Slow! Or with counter-Haste...
But Prayer also works great, especially if there is no Earth or Air magic (I like Knights in Heroes 3, so I often have to rely on Water)
In general, this case with constant blinding, which Slonysh described, is very similar to Heroes 2, but in the third game, it's much harder to achieve... Of course, it's possible, but it's much more difficult to do.