Explosion

Fireball may be a good weapon against weaker foes, but the stronger ones are not usually affected by it. But as your foes become stronger, there also comes available the more potent attack spells, like this one. Explosion sends out a regular fireball, but on contact it explodes with the force of a powder keg, causing massive destruction.

This spell is not only good for killing tougher foes, but also to blow up massive doors and other obstacles.

Note that the Ultima VII Part Two version of this spell uses blue fire, instead of the regular red-yellow fire.