Trap Magic

When you cast this spell, you set a glyph that later unleashes a magical effect. You inscribe it either on a surface (such as a table or a section of floor or wall) or within an object that can be closed (such as a book, a scroll, or a treasure chest) to conceal the glyph. The glyph can cover an area no larger than 10 feet in diameter. If the surface or object is moved more than 10 feet from where you cast this spell, the glyph is broken, and the spell ends without being triggered.

The glyph is nearly invisible and requires a successful Intelligence (Arcana) check against your spell save DC to be found.

You decide what triggers the glyph when you cast the spell. For glyphs inscribed on a surface, the most typical triggers include touching or standing on the glyph, removing another object covering the glyph, approaching within a certain distance of the glyph, or manipulating the object on which the glyph is inscribed. For glyphs inscribed within an object, the most common triggers include opening that object, approaching within a certain distance of the object, or seeing or reading the glyph. Once a glyph is triggered, this spell ends.

You can further refine the trigger so the spell activates only under certain circumstances or according to physical characteristics (such as height or weight), creature kind (for example, the ward could be set to affect aberrations or drow), or alignment. You can also set conditions for creatures that don’t trigger the glyph, such as those who say a certain password.

When you set the glyph, choose Explosive Trap , Spell Trap, Flash Trap,  or Counter Trap.  

Explosive Trap. When triggered, the glyph erupts with magical energy in a 20-foot-radius sphere centered on the glyph. The sphere spreads around corners. Each creature in the area must make a Dexterity saving throw. A creature takes 5d8 acid, cold, fire, lightning, or thunder damage on a failed saving throw (your choice when you create the glyph), or half as much damage on a successful one.

Spell Trap. You can store a prepared spell of 3rd level or lower in the glyph by casting it as part of creating the glyph. The spell must target a single creature or an area. The spell being stored has no immediate effect when cast in this way. When the glyph is triggered, the stored spell is cast. If the spell has a target, it targets the creature that triggered the glyph. If the spell affects an area, the area is centered on that creature. If the spell summons hostile creatures or creates harmful objects or traps, they appear as close as possible to the intruder and attack it. If the spell requires concentration, it lasts until the end of its full duration.  

Flash Trap.  When triggered, the glyph emits a blinding light.  All creatures withing a 30ft. radius of the glyph must make a constitution saving throw.  On a failed save, the creature takes 4d4 radiant damage and is blinded for 1 minute.  On a successful save, the creature takes half as much damage and is not blinded.  

Counter Trap.  When triggered, the glyph absorbs a ranged spell's power that is withing a 25ft. radius and disintegrates the spell.  After disintegrating, the glyph fires the same spell back at its caster with an additional 3 damage dice.  The spell which is being deflected must be a 3rd level spell or lower, otherwise the trap has no effect on the spell.  

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage of an explosive trap glyph increases by 1d8 for each slot level above 3rd. If you create a spell trap, you can store any spell of up to the same level as the slot you use for the spell Magical Trap.  If you create a Flash trap, the damage increases by 2d4 for each slot level above 3rd.  If you create a Counter Trap, the damage increases by one damage dice for each slot level above 3rd.   Also, the glyph can absorb and deflect spells of the same slot level used when casting this spell  and below.  For example, if the spell Magic Missile  is cast using a 4th level slot, the spell is able to be absorbed and deflected if you cast this spell using a 4th level slot or higher.  If you cast this spell using a 3rd level slot in the same scenario, the Magic Missile would not be absorbed and deflected.