This topic is all about magic in video games. I'll be making a short survey you can take telling us what you think about magic, and you can discuss whatever else you want... as long as it relates to magic!

Best: Destruction (Morrowind). Sure, you could go at each other with axes. Or how about you cast a spell that inflicts the Disintegrate Weapon and Disintegrate Armour effects on them? Laugh as your enemy can no longer use that weapon they're holding! Or just throw fireballs at them...

Worst: Turn Undead (Some RPGs I can't think of?). Here's a better one for you, Turn Undead (into dust). Required component, +1 Warhammer of Kickass.

Most Underrated: Poison (Most RPGs). When you're playing an assassin, poisons are essential. Use them, nothing worse for a target to get stabbed from behind with a poisoned weapon that causes paralysis. Also, if you want to be rid of a hard enemy quickly, all damage done counts. Poison their ****.you get some free hits in if it works.

Most Unique: Sketch (Final Fantasy 6). I don't think the theme of pictomancers has ever been touched upon since this game. Maybe I just missed it. However, I do believe the ability to copy enemy skills through the art of drawing is the most unique form of "magic" I've ever seen in a game.

Best Buff: Regen, or varients thereof (Final Fantasy & other RPGs). I'm with viLky. Nice constant heal. Also, by taking advantage of the way the Playstation worked, you could use a single regen to heal your party during a battle in FF7.

Worst Buff: Invisibility (Morrowind). Works well...if you don't plan on doing anything. Attacking or activating things breaks the spell and makes you visible again. If you can get a spell or an item with the chameleon 100% effect, it does the same job without the downside of disactivating when doing anything but jack ****.

Best Single Spell: Escape, or varients thereof (Most RPGs). Sometimes, luck decides to tell you to get ****ed and throws you into a hard battle. Too hard. And while it works sometimes, Run does not work all the time, and there are times you want it to just work RIGHT ****ING NOW. That's where this comes in. Cast the spell, away you go. Also useful in Morrowind, as it allows you to haul your loot back to the closest city ASAP.

Best Team Spell: TIE, Reflect & Shield or varients thereof (Final Fantasy & some other RPGs). Sure, Reflect sucks if you want to cast a spell at your team. However, in a couple of FFs I've played, it works well as a cheat to attack your enemy 3 times with a single spell. Cast reflect, cast an attack spell at your party, watch as it bounces off to attack your foe for 3x the amount of damage it usualy would.
Shield, on the other hand, is good for protecting the party. Less damage done is always better, shield allows that.

Coolest Looking: Bahamut ZERO (Final Fantasy 7). You're basically summoning a living orbital cannon. Awesome. Safer Sephiroth's Super Nova would go here...if it weren't so damned long. I could have made a coffee in the time it takes for that to hit.