Read Foe

You can exploit your opponent’s tells in the heat of battle to gain an edge in defeating them.

Sense Motive 3 ranks

You can study your opponent using Sense Motive as a move action. The DC is 15 + 1-1/2 × the target’s CR and the creature must have an Intelligence score of 3 or higher. On a success you either gain a +2 insight bonus to your next attack of opportunity against that foe or gain a +1 insight bonus to AC against the next attack from that foe, whichever occurs first before the start of your next turn.