how do you dealing with black dragons as a mage ?

[Leind]

Another little trick I found useful is that while Blackies are immune to magic, they still can be freezed. When I use Ice snake on an adjacent troop (generally that big stack of red dragons), the blackies take no damage but are slowed down by the freeze effect.

Usually that mean that they can't attack during the first turn, and as I use high initiative units two full turn are enough to do a lot of damage.