My reason for not suggesting any skills in the form of "Taunt" is because it wrestles character control away from your opponent immediately. If you design it to aggro nearby enemies into attacking the shield bearer for one turn then it's essentially an AOE CC that bypasses the physical/magical armor design. Also the only real counter to it is to kill off the taunter. I feel it's going to be problematic for the AI to deal with and not so fun in the multiplayer arena.
On the other hand, I do think that it's better to balance shield by providing utilities as opposed to simply taking away the AP cost. To highlight the tank archetype, a large amount of skills/talents for shields should center around mentally provoking your opponent into focusing on the shield user. Not by a direct taunt that forces them to attack him, but rather because it is the safest/most reasonable course of action. If your opponent is spending precious resource & AP to deal with your shield, then it's doing the job of a tank already even without taunt.
