This skill has multiple uses: you can use it with the target 'enter spiritworld' to enter the spirit realm, target it at a monster to check if it is enslaving ghosts or target it at a ghost lily to remember a fallen innocent. A ghost is required to enter the spiritworld, to act as a guide. The more powerful the guide, the deeper you will find yourself in the realm of ghosts, and the benefits of the realm are greater. Checking monsters is easier than entering the realms, and thus less time-consuming. Also, you don't need a ghost to check a monster.
The spiritworld is a dangerous place, but it offers great power to those who master its secrets. The inhabitants of the realm are many, and most of them are hostile. Some, on the other hand, are beneficent, and it is said that some (others say most) secrets of the order of ghost liberator paladins were brought back from the spiritworld by Samuel de Montfort and those who follow his footsteps. In the spiritworld you can seek guidance or try to get a task from one of the inhabitants.
While some of the order see using this skill to check a monster as an act of greed, all approve the general training of this skill, for its use as the key to the spiritworld. It is also a common topic to debate if greed is such a bad thing - you are liberating ghosts after all, and sometimes knowing how to liberate the most with the least effort can be very useful.
Usage: use holy seance at <monster> use holy seance at enter spiritworld use holy seance at lily