Tactics against Necromancers.

dnaop-wr, but this is a special and rather rare case, and in general, I wouldn't rely on an explosion. Besides, it's worth remembering factors such as: magic resistance (skill + artifacts), Cloak of Negation, cursed ground, Sphere of Inhibition... Magic can fail in such cases. And also remember that a lot of mana is needed for an explosion (in online games, I think there can never be too much of it).