Pulses mainly serve as magical probes. Once sent out into a target area, they will return shortly with an approximate ballpark of magical strength in said area. This ballpark is not necessarily triggered by the strength of other magical spells operating within the vicinity; rather, it appears simply to react to the presence of anything magical, such as seven-league boots. It is implied that Pulses function by absorbing a slight amount of magic from their surroundings. It is unknown if they serve any other function.
Pulses appear as gently glowing orbs of energy. Both size and direction of movement can be directed by the caster. If in the presence of strong magical energy, Pulses will turn a "virulent red-orange". Otherwise, if no magic is in the vicinity, Pulses will slowly lose magical energy and eventually fade.
Usage Details Edit
It is unknown what level of power is required to create a Pulse. Moderately powerful demons like the djinni Bartimaeus are able to create Pulses with ease, suggesting that imps and foliots could potentially cast the spell. As the spell itself requires little magical expenditure, Bartimaeus uses the spell several times to gauge the risk level of entering a room.