Campaign: Dungeons of Drakkenheim
Researching the Spell: A character who can cast 5th level spells, knows the Purge Contamination spell, and has created at least 1 dose of Aqua Expurgo may research Neutralizing Field. To complete the research, the caster must spend 25 days of downtime and 1250 gp.

You negate contaminated magical energies in a 10-foot radius sphere. Until the spell ends, the sphere moves with you, centred on you. Creatures in the sphere (including you) can’t gain contamination levels and have immunity to necrotic damage. Contaminated spells can’t be cast by creatures in the area.