Can a magus employ in his off-hand a ring of force shield and still use Spell Combat?

Question

Is there anything preventing a magus from using Ring of Force Shield with Spell Combat?

Answer 1

A Magus can use a Ring of Force Shield and still use Spell Combat, just not at the same time.

The description for a Ring of Force Shield says:

This ring generates a shield-sized (and shield-shaped) wall of force that stays with the ring and can be wielded by the wearer as if it were a heavy shield (+2 AC). This special creation has no armor check penalty or arcane spell failure chance since it is weightless and encumbrance-free. It can be activated and deactivated at will as a free action.

See my emphasis there. The shield is still wielded, like any other shield, meaning that your off hand is not free while it's out. However, as it's a free action to activate and deactivate the shield, you can use use it as follow:

1. Beginning of turn, free action to deactivate Ring of Force Shield
2. Use Spell Combat
3. Before finishing your turn, another free action to reactivate Ring of Force Shield

It is worth noting, though, that the rules about free actions do leave an opening for a GM to decide you're taking too many free actions in a turn, or abusing free actions, but I've never actually seen a GM make this sort of ruling.

Additionally, you could accomplish the same thing with a Quickdraw Shield and the Quick Draw feat. This will also allow you to both hold and stow the shield as a free action, and use the same steps as listed above.

If you have a base attack bonus of +1 or higher, you may don or put away a quickdraw shield as a swift action combined with a regular move. If you have the Two-Weapon Fighting feat, you can draw a light or one-handed weapon with one hand and a quickdraw shield with the other in the time it would normally take you to draw one weapon. If you have the Quick Draw feat, you may don or put away a quickdraw shield as a free action.