You can create realistic phantasms of one sense, usually sight. With two picks, you can create full sense illusions. Phantasms are usually static, but you can make them move around as a continuos action.
These Phantasms are very realistic, but you must be familiar with whatever you are mimicking, or it will seem unreal to onlookers. To create a believable Phantasm takes a Powers roll against your targets' Perception. If your target knows more about whatever you are imitating than you do, or if the phantasm lacks a sensory component relevant to the situation, the difficulty is his highest Action Value. Regardless of whether the Phantasm is believed or not, it still persists, disbelief does not cause it to vanish. Striking one hard will dispel it, however.
This is usually played out as Stunts using Powers against Perception or Deceit.
If you want your illusions to attack, purchase a Spectral Blast with Animate.