This may be inscribed around a summoning circle.

Binding 15 [9] 
    Unbreakable [+40%] 
    Area Effect (4 yard radius) [+100%] 
    Variable [+5%] 
        Allows Size Reduction 
    Delay (Triggered) [+50%] 
        Were Creature Entering Circle 
    Environmental [-40%] 
        Must be within 1 yard of surface 
        Must be inside circle 
    Environmental (Night of the Full Moon, Rare) [-40%] 
    Terminal Condition [-20%] 
        Can be disrupted by marring the circle externally 
    Terminal Condition [-10%] 
        Sunrise ends the spell 
    One-Shot [-10%] 
    Preparation Required (1 hour) [-40%] 
        Drawing the binding circle 
        May be re-used [-20%] 
    Preparation Requires Skill Roll (Symbol Drawing) [-5%] 
    Takes Extra Time 6 [-60%] 
    Magical [-10%] 
    Spell Components [-30%] 
        Must chant in Latin 
        Must sprinkle powered silver on circle ($10) 
Levels 2+ [+3/level] 
    Increase Binding by 5 [+2 base]