Magic circle against evil Magic Circle against Evil , also known as Protection from Evil , 10 ' Radius , was an abjuration spell that created a sphere of warding against mental and physical attacks from evil creatures . The older version of this spell was reversible , called Protection from Good , 10 ' Radius , and had identical effects on good creatures . Effects . This spell conferred the same benefits as " protection from evil " to the creature touched , except the aura extended to a 10 ft ( 3 m ) radius sphere around the creature , and warded all those within the area of effect . The barrier prevented nongood summoned creatures from entering unless they managed to resist the spell . If the creature touched was too large to fit completely within the sphere , then the spell acted as a " protection from evil " spell for that creature . The " protection " lasted for tens of minutes to a few hours , depending on the experience of the caster . The newer version of this spell could be inverted to prevent nongood summoned creatures from leaving the circle drawn to cast the spell ( see Components below ) . The creature had to be summoned immediately after the " magic circle " was empowered , and if successful would bind the creature inside the circle for many days . This circle was very fragile to all except the creature being imprisoned , so extreme caution had to be exercised to prevent even so much as a piece of straw from bridging the circle , breaking the spell and releasing the prisoner . Ranged attacks and spells in either direction were not stopped by the circle . The " magic circle " was also permeable to dimensional travel ( " astral projection " , " blink " , " dimension door " , " etherealness " , " gate " , " plane shift " , " shadow walk " , " teleport " , etc . ) unless strengthened by a " dimensional anchor " spell , either cast on the creature just after it was summoned ( risky , because the creature had an opportunity to resist and / or act ) or as part of the preparation of the " magic circle " ( safer , but required a delicate , time - consuming act of Spellcraft ) . To bolster the " magic circle " with " dimensional anchor " required the drawing of an intricate tracery with no gaps or breaks , adorned with various magical sigils , all around the perimeter of the circle . This task took at least 10 minutes to complete and was difficult to perform successfully when under duress . If not pressed for time then the caster had the luxury of making sure the augmenting figure was complete and was practically guaranteed success . Once the tracing was finished , the " dimensional anchor " was cast just before the creature was summoned into the circle . The creature could not resist , dimensional travel was denied , and ranged attacks and spells or abilities could not cross the augmented circle . Anything that disturbed or bridged the circle immediately canceled the spell and released the prisoner , but the imprisoned creature could not directly or indirectly cause this to happen by its own actions . This spell did not stack with " protection from evil " or vice versa . Components . For the newer version of the spell , verbal and somatic components were required plus the caster had to draw a 3 ft ( 91 cm ) circle around the recipient using powdered silver . For the containment version , this silver trace had to be full size ( 20 ft / 6 . 1 m in diameter ) and could not be breached , disturbed , altered , or bridged for the duration of the spell or else the spell was canceled . For the older divine version , the circle was traced with holy water ( on the ground ) or burning incense ( in the air ) . If the spell was cast in reverse for " protection from good , 10 ' radius " , the circle was drawn with unholy water or smoldering dung or blood . For the older arcane version , the circle had to be full size ( 20 ft / 6 . 1 m in diameter ) and made of powdered silver to ward off evil and powdered iron to ward off good .