In Shadowrun, a focus is a magical item that is used by a mage or shaman to increase their capacities. They come in a number of flavors- Spell foci provide extra dice for casting and drain resistance, Spirit foci assist with conjuring a specific class of elemental or nature spirit, weapon foci are hand-held weapons that are effective against creatures resistant to them, and power foci allow a magician to throw stronger spells and do more with magic in general. They are bonded to the magician who paid the karma for them, and thus only that magician will be able to use them for their power.

In Mage the Ascension, foci are (usually mundane) tools that assist a willworker in his goals. While they are used by both members of the Traditions and members of the Technocracy, their nature varies greatly depending on how the mage was taught; foci from the Traditions can be anything from carving runes into one's arm (Verbena practice) to a pair of dice (Euthanatos and Hollow Ones) to a clockwork organism roaming the virtual world (Sons of Ether and Virtual Adepts). Technocracy willworkers tend to use more technological foci- holding and pointing a plasma weapon at a reality deviant, cybernetic implants granting inhuman strength, rebonded nanites restitching flesh on the cellular level, and more. What gives the mages of the Traditions an advantage is that they ultimately begin to realize that it is THEY who are responsible for magic, and the tools are just that- tools. Technocrats cannot afford to realize this, and as such, they are forever bound in their magic to things of the flesh.