Hawken said:
If you read the description of KS it mentions, "If you hit with your attack of opportunity both you and your opponent deal and take damage simultaneously". This implies that the feat triggers only on melee attacks that inflict damage. Grappling doesn't do that.
If you read the description of Karmic Strike?
"... the ability to make an attack of opportunity against any creature that makes a successful melee attack or melee touch attack against you."
Starting a Grapple
To start a grapple, you need to grab and hold your target. Starting a grapple requires a successful melee attack roll. If you get multiple attacks, you can attempt to start a grapple multiple times (at successively lower base attack bonuses).
Step 1: Attack of Opportunity. You provoke an attack of opportunity from the target you are trying to grapple. If the attack of opportunity deals damage, the grapple attempt fails. (Certain monsters do not provoke attacks of opportunity when they attempt to grapple, nor do characters with the Improved Grapple feat.) If the attack of opportunity misses or fails to deal damage, proceed to Step 2.
Step 2: Grab. You make a melee touch attack to grab the target. If you fail to hit the target, the grapple attempt fails. If you succeed, proceed to Step 3.
Notice: the grab requires a melee touch attack, that succeeds.
If you do this, you've made a successful melee touch attack.
"
... the ability to make an attack of opportunity against any creature that makes a successful melee attack or melee touch attack against you."
Step 2 of Starting a Grapple, if successful, provokes an AoO from Karmic Strike.
Notice also that the AoO for initiating a grapple occurs in Step 1. The AoO from Karmic Strike doesn't occur until Step 2 is resolved (was the touch attack successful?) They are, in fact, separate opportunities... and someone with Combat Reflexes and Karmic Strike could take both, though if the first deals damage, the second opportunity never occurs.
1. Character A attempts to initiate a grapple. In step 1, character B gets an AoO. If he deals damage, the grapple is thwarted. If not, we move onto step 2.
2. Character A makes a melee touch attack. If he's successful, Karmic Strike triggers, and character B gets an AoO (though dealing damage will not automatically thwart the grapple), and we move on to step 3. If he fails, Karmic Strike doesn't trigger, but the grapple is unsuccessful.
What book are you reading that says Combat Expertise is a prerequisite for KS? It isn't. Dex 13+ and Dodge are the only requirements for KS.
Um, unless stated otherwise, we assume 3.5. Try the 3.5 version of Karmic Strike in the Complete Warrior.
Of course the 3E version of Karmic Strike doesn't require Combat Expertise. It wasn't called Combat Expertise in 3E.
In 3.5, Combat Expertise is a prerequisite.
-Hyp.