Shielded Caster

Whenever a character with this talent is adjacent to an ally who also has this feat, they receive a +4 competence bonus on concentration checks.

If the ally is wielding a buckler or a targe, this bonus increases by +1.
If your ally is wielding a kite shield, heater shield, or a tower shield, this bonus increases by +2.
Finally, if an enemy threatening the character and the ally has the Disruptive feat, or another ability that increases the DC of concentration checks, the amount of the increase is halved.