One of the cool things about the original Dungeons & Dragons and Advanced Dungeons & Dragons games is that you can reverse certain spells. This causes the spell to have an effect that is essentially the opposite of the normal version. Instead of Continual Light you could cast Continual Darkness, merely by memorising the spell backwards. Better yet, clerics could reverse some of their spells at casting time, simply by incanting them backwards. So instead of Cure Light Wounds you could do Cause Light Wounds. It was noted, however, that good clerics using reversed spells are potentially putting their good alignment standing at risk.

This feeds back into any game in which magical, mystical, or even ultra-technological effects occur. Get something slightly wrong, or have one of the conditions not completely satisfied, and you can justify pretty much anything happening.

Transcript

Mace Windu: Enough talk. You know what? I'm gonna deliver justice. Right here. Right now.
Anakin: Nooo!!
{Palpatine defends himself against Mace with Force Drain}
[SFX]: KRZZRKZKZZZZT!
[SFX]: KRZZRKZKZZZZT!
{Palpatine's face is deformed as Mace deflects the Force Drain back at him with his laser sword}
[SFX]: Krzzrzzt!
[SFX]: Krzzrzz...
[SFX]: Zzzt!
[SFX]: Krzzrzzt!
[SFX]: zzt... zzzt {Force Drain dies away, Palpatine is left horribly disfigured}
Palpatine: Whoops! Had the silly thing in reverse.