The elemental shields granting Elemental affinity is a neat and simple idea. I think though that the current balance issue with Elemental Shields is that they absorb all kinds of damage, not just the type that they are supposed to, so that might need to be looked at when re-balancing Elemental Shields. A +3 AP cost might be okay, but I'd prefer +2 AP.
+3 AP is quite boost in case of affinity works.
Lets do a math -
Shield costs 8AP
Shield stays on for 3 rounds
you can cast 3-8 spells.
Every spell is 1AP less
At worst case, it is the same like now
At good case, caster is shielded and cost it nothing.
At best case, caster is glasscanon so he gets AP bonus and is shielded. e.g. This negates the glasscanon drawback!
On the other side, give the expensive shield to the melle character is not so benefical.
I think that make mages more into elements is way of the game.
The shields power could be little less, 80% of current HP.
