Mage Hand
When you cast this spell, it becomes a situational Aspect that lasts for the rest of the scene. That Aspect occupies a zone. Each Exchange, you can move it one zone independently from yourself. The magical hand is invisible but can be sensed by creatures that sense invisible objects.
You can Invoke it for effect to manipulate, but not damage, objects as if it were your own dominant hand. You may use any skill you possess. For example, you could attempt to pick a lock using Burglary or pick up a knife and stab someone using Fighting.
While the spell is active, you can spend your turn to Create an Advantage (using your Magic skill) and gain additional free invocations, if you succeed.
Note: Outside of an Exchange, the character can use Mage Hand to accomplish tasks at about half the speed they could using their natural hand. This corresponds to Creating an Advantage one Exchange and using the free invocation on the next -- but you don't actually need to roll dice or narrate that if you're outside an action scene.