As part of the discussion of the magic system, we asked, "What is the role of a wizard in a delving band?" There's a lot of ways to answer that question, but I want to lay out something I think is a common view.
What Should a Wizard Do
A wizard is a master at dealing with the weird stuff: magical items, magical traps, magical foes. He has less utility against mundane foes.- Fighting diffuse and insubstantial foes - No matter how skilled the swashbuckler or scout is with blade or bow, they're going to have a hard time killing a living tornado or an animated cloud of fire, or even engaging a creature that lives on another plane of existence. Fighting these creatures is where the wizard should shine.
- Fighting puzzle monsters vulnerable to certain elements - Abominable snowmen, magma monsters, water weirds, and all kinds of other weird creatures can be killed by mundane means, but can be killed more efficiently by using the appropriate elemental counter-effects. A knight might have a flaming sword or a ninja might have a Liquid Ice grenade, which can deal with some subset of these creatures, but a wizard should have a range of abilities that let him exploit vulnerabilities.
- Crowd Control and Ability Shutdown - A wizard shouldn't necessarily be able to kill every foe, especially mundane foes like a horde of orcs. But he should be able to use magic to break up their clusters and force them to engage in smaller, more manageable groups. Creating barriers for instant choke-points or walls to prevent enemy arching from massing fire should be an essential part of the wizard's repertoire.
- Dealing with Magic - As the magic guy, a wizard should know about magic. He should be able to analyze magical items, identify and counter magical curses, and dispose of magical hazards and threats.
What a Wizard Shouldn't Do
Part of the problem with most RPG magic systems is that magic quickly becomes a license to do everything, eventually leading to the failure of quadratic wizards, linear fighters. Magic needs limits, and there should be some things that a wizard doesn't do.- Devastating Direct Damage - A wizard needs to contribute to a fight against mundane foes, but his attacks shouldn't be show stoppers. When fighting something like a dragon or a giant, a wizard should be able to chip away at the monster, but not fast enough to kill it before the monster kills the wizard.
- Scouting - The wizard shouldn't be the primary scout. Letting him augment the primary scout through spells, or use his spells to be an assistant to the primary scout is fine, but he shouldn't be betting at sneaking and noticing stuff than the primary scout.
- Bypassing Obstacles - The wizard also shouldn't be the first choice to go to in order to get past an obstacle, whether that obstacle is a locked door or a bottomless chasm. I'm torn as to whether it's better to forbid wizards the abilities to easily bypass obstacles, or just make the opportunity cost of doing so high enough that people prefer to ask someone else to give it a go first. If it takes 1/3rd of a wizard's daily magical ability to open a locked door, people are going to bring a thief along.
How Does the Dungeon Fantasy Wizard Stack Up?
If the role of the wizard is to deal with diffuse and other weird foes, crowd control mundane foes, and not steal niche from thieves, martial artists, and scouts, then the DF Wizard is a mixed bag.On the plus side, spells such as Concussion, Flash, Shape Earth/Air/Fire, Stench, Grease, and Glue make the wizard good at mundane crowd control. Most wizards have access to a variety of elemental effects, and can help exploit elemental vulnerabilities. Wizards know about magic.
On the down side, the ability to build up massive 9d+ missile spells means that wizards can potentially deal devastating direct damage, though very slowly and with low hit chances. Wizards can scout by casting Invisibility and Mage-Stealth, though it's probably more useful to cast those spells on a Scout or Thief and let them sneak ahead. They can also Created Servants to find traps or danger, but those Servants aren't really good for finding some of the weird traps or noticing anything hidden. Constantly renewable fatigue, low prerequisite chains for useful spells like Lockmaster or Walk on Air, and low energy costs for those spells means that wizards can easily bypass obstacles and invade other people's niches.
Most regrettably, wizards aren't amazingly good at dealing with diffuse foes. Explosive missile spells take a lot of time and energy to cast in order to reliably deal with a single diffuse foe. A Mystic Knight with Shockwave (Bow) can do 1d+4 im exp to diffuse foes every round or two for a single fatigue point; a wizard casting Explosive Fireball is spending 2-3 FP for the same level of damage.
My article on Rationalizing Damage Spells addresses several of these issues, and using Threshold Magic (to force wizards to ration their power on a daily basis) and/or increasing the costs of some of the more problematic spells (Lockmaster at 12 FP is only going to get cast if the thief is dead) would do a lot to address the others.