Althor's Arm

Background: Althor the One Armed is well known as a master spell creator specializing in force field spells of great elegance and complexity.  He was started down this path when he barely survived a gnoll attack as a young fighter mage (Ax Specialist) by improvising a V only magic missile spell to kill the gnoll that had just ripped off his right arm. He went on to develop a whole class of force field based spells of which perhaps the best known are his Althor's Arm, Althor's Return and Althor's Ax spells.

Casting Restrictions: All of Althor's 1st level spells require at least a 15 INT to learn and cast. All of them are cast as a 1 minute ritual which embeds a spell pattern into the creature or item to be affected or who will be triggering the spell. Once the ritual has been cast the spell can be triggered  as either a reaction or an opportunity action by EITHER a quick 1 hand gesture OR a single keyword as a reaction. If cast as a full ritual (11 minutes cast time) the spell counts as a standard ritual spell. If the shorter ritual is used, then a spell slot is used up.

Spell: Althor's Arm

If cast upon a limb that already has a lower level Althor's Arm or Appendage spell upon it, the lower level spell will be overwritten and replaced with the higher level spell. Attempting to cast a lower level spell on a limb that already has an equal or higher level spell active will fail. 

Restriction: May only be used on humanoid creatures of less than 12' height and will be canceled if the creature shape changes or is polymorphed after the spell is in force.

Once triggered the spell creates an invisible arm of force at the point of attachment with the results depending on the situation.

Case 1: Replacing a missing arm. Creates an invisible arm of for at the point an arm is missing which can be used just as if it were an ordinary arm for the creature, although the arm, being force, is immune to normal, non magical conditions such as fires, acid, poison, etc. 

Case 2: Overlaying an existing arm. Creates an invisible sheath of force over one specific arm which has the following effect:

a. Arm holding a weapon: +1 to hit and damage. Arm doesn't touch and is therefore not affected by non magical affects requiring skin contact.

b. Arm holding a shield or parrying weapon: +1 AC to attacks that the shield or parrying weapon could be used against. Arm doesn't touch and is therefore not affected by non magical affects requiring skin contact.

Note: same effects from this spell don't stack so with 2 spells you could have +1 attack, +1 AC, but NOT +2 AC or attack.