Serren's Armor Lock

Transmutation
Level: Artificer * 3, Magus * 2, Sorcerer */Wizard * 3, Warlock * 3
Components: V, S, M (a pinch of rust)
Casting Time: 1 Standard Action
Range: medium (100 ft. + 10 ft./level)
Target: one armored creature
Duration: 1 round/level (D)
Saving Throw: Reflex partial, see text
Spell Resistance: yes
  Upon pointing at an armored foe, you cause all of the joints of the target's armor to stiffen as otherworldly chains wrap around the target. On a failed Reflex Save, a target in heavy metal armor becomes Staggered. A target in light or medium metal armor instead becomes Entangled. Targets wearing no armor or nonmetallic armor are unaffected. If the target is wearing heavy metal armor and succeeds at its Reflex Save, it becomes Entangled instead of Staggered; a target in light or medium metal armor that succeeds at its saving throw is unaffected by the spell.