Arachnus Spinner has an activated ability that allows you to tap a spider you control to search your library for a card named Arachnus Web and put this into the battlefield attached to a targeted creature. This ability can be used even if you do not have any copies of Arachnus Web in your library. In most cases, this will not result in anything more than you searching, failing to find and shuffling your library. But as this ability does target, it can be used to destroy Illusions with the ability that causes them to be sacrificed when they are targeted, like Phantasmal Bear.