Mystical love is the the love that a mystic has towards the supreme being. The supreme being is not some abstract daddy up in the skies, but the supreme being is existence, formless and ageless permeating the universe at all times. It has no distinguishable qualities, it is the eye of consciousness. Mystical love is the love a separate self cultivates towards that pure nexus of reality, he finds himself mesmerized by its subtlety and beauty, and finds himself ultimately dissolved in its ineffableness.
The love of a mystic is one of the highest forms of love, resembling that love that parents have towards their children. Universal and unconditional.