Device Magic is magic performed with some form of mystical device or relic. In this sort of system, the only magic that can be done without some sort of potion or magic item is the magical creation of potions or magic items. (Heck, you could remove that loophole and create a The Chicken Or The Egg scenario instead).
This is a very common version of magic for Dwarves and Gnomes. Practitioners of this style of magic are likely to fall into the Mad Scientist or Ultimate Blacksmith archetypes. Instead of a Wizard's Tower, they'll have a Forge.
This also works very well for the mythic trope of the magician who absolutely requires a given item to work their magic - a magic mirror, crystal ball, cauldron etc.. In these cases not only are they powerless without it, but the backlash from destroying it may well be fatal to them.
Game and Story Use
- Make sure you consider the impact on your fantasy economy, and the potential for Power Creep. When making magic items is the only thing a wizard can do, you can expect any wizardly PCs to want to make a lot of them.
- This might actually be quite a good way to add downtime to your campaign - if it takes months to make a magic item, adventures can be widely spaced as the party waits for the wizard to make up a batch of consumables for their next trip.
- Alternatively, can the class and level system rules and get one that allows characters with a more widely focused skill set.
- A little bit of Device Magic can be dropped into an otherwise Low Fantasy setting, especially if making a magic device takes expert skills and years dedicated to the craft. Two or three feuding Ultimate Blacksmiths, each churning out one magic item a year, can allow a little magic into the system without it infusing everything.
- In such a setting, those items will likely be highly prized, at least amongst those in the know. Think Hattori Hanzō from Kill Bill.
- It's possible a player character may be defined by his one and only magic weapon, like Elric and his sword.
- This works well for a limited magic campaign - if, rather than throwing fireballs and lightning bolts at people in battle, wizards are limited to producing magical items, you can achieve a very different feel to "generic fantasy".
- The cRPG Darklands is a good example of this - most of the "magic" in the game is actually alchemy and your party "wizard" needs to make up his concoctions well in advance of a fight.