Gaming

Elder scrolls oblivion: crafting your own spells. Applying fire, electric, or ice damage to the spell. If you apply over 25 of one damage type, you'd need to have an advanced Destruction skill level to use that spell. But if you apply 24 of all 3 damage types to one spell, you could still cast it at lower Destruction level. So you as a low level destruction mage could be casting a 72 damage spell that uses all 3 damage types, but you can't cast a 25 damage spell that uses one of those damage types.

Edit: the downside was the 72 damage spell would probably use up all your mana in one attack, but hey it was still a useful damage exploit