Alarum's Answer

The natural complement to the alarum spell, it allows you to instantly respond to an activated alarum. If you see or sense the activation of an alarum, you can use cast this spell to instantly travel to the location of the paladin who set the alarum off. When you do so, you appear in the nearest unoccupied space to the paladin.

This spell functions over any distance without fail, barring interference from other magical sources. It cannot pierce the barriers between planes, however.