One such “scoobie spell” involves Willow making use of the four elements, within an incantation to “ionise the atmosphere around us”, with the aim of interfering with an electric tracer signal (that’s being emitted from Spike). At the time, stopping the tracer is important, because it was embedded by “The Initiative” (a secret government operation), which the scoobie gang believes are “up to no good”.
In time, this is proven to be so, and Buffy encounters an opponent that she has trouble defeating: Adam (a hybrid demon/human/machine). With Willows growing power, she is eventually able to cast the dangerous “Adjoining Spell” (which is fundamental to helping Buffy defeat Adam). The spell involves speaking several incantations (assisted by candles and spirit cards) with the aim of combining: spirit (Willow), heart (Xander) and mind (Giles) within strength (Buffy), to create a single “being”. The “being” (an “Uber Buffy”) is then easily able to destroy Adam (by ripping his uranium power source from his chest).