Secondary skills in Heroes 3.

The most useful magic is earth magic. Very good spells include: town portal, slow, and explosion. Air magic is also quite good (haste, dimension door, fly, chain lightning).

Earth magic has a level 5 spell, I don't remember the name, it looks like a cauldron... disintegration (impolation) or something like that... it's a powerful spell.

This spell is called explosion.