Editing TROS in the Hammer:Magic Spirits (section)

==Effect Target Number (ETN)==
Combine this level of effect with the other parameters (target, range, volume) as sorcery to determine the effect target number (ETN).  Modify the ETN by -1 for each of the primary qualities the spirit includes.

Example:
* the desert demon is going to create heat, as above.  A level one effect might require everyone in the room to roll End versus the 5+number of successes or be fatigued while they are in the room.  A level two effect might require everyone in the room to roll the equivalent of a Blood Loss Roll vs. 7+number of successes every three rounds as long as they are in the room, and take a penalty equal to 10-Endurance on all physical activity.  A level three effect would cause all flammable objects in the room to combust, and all persons in the room to continue to take number of successes in damage levels (randomly distributed) every round in wounds.