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Zajimarn's Field of Icy Razors

(Magic of Faerun)

Evocation [Cold]
Level: Sorcerer 8, Wizard 8,
Components: V, S, AF,
Casting Time: 1 action
Range: Medium (100 ft. + 10 ft./level)
Area: One 10-ft. square/level
Duration: 1 minute/level
Saving Throw: Reflex partial
Spell Resistance: Yes

Razor-sharp ice crystals fill the area.
Creatures standing in the area at the time the spell is cast take 2d4 points of damage plus 1d6 points of cold damage +1 point/level.
Any creature moving on foot into or through the spell's area takes this damage for each 5 feet of movement through the razored area.
Any creature that sustains normal damage from this spell must also succeed at a Reflex save or suffer injuries to its feet and legs that slow its speed by one-third.
This speed penalty lasts for 24 hours or until the injured creature receives a cure spell (which also restores lost hit points).
Another character can remove the penalty by taking 10 minutes to dress the injuries and succeeding at a Heal check against the spell's save DC.
Each 5-foot square section has effectively 20 hit points.
Even when all the ice has been destroyed, frigid air remains in the area and deals 1d6 points of cold damage +1 point/level to creatures that pass through it.
Focus: A silver shuriken worth 50 gp that looks like a snowflake.