Corpse Skin

You speak the words, "In Aglo Corp Ylem" as your target a creature in range. 

A creature must make a Constitution saving throw.  On a failed save, the creatures skin visibly begins to rot.

If a creature is immune to fire or poison damage, they now become vulnerable.

If a creature is vulnerable to fire and poison damage, they now take and extra 1d8 damage per level of spell cast.