angry monkey said:
Whenever you get an attack from expert tactitian, it's a sneak attack by it's nature.
Not necessarily.
Let's say in round 1, I feint successfully. Against my next melee attack, you are denied Dex bonus... but until I make that attack, you aren't, so ET doesn't trigger yet.
Next round, I make a full attack. Against my first attack, you are denied your Dex bonus... therefore you are now an opponent denied his Dex bonus, which means that dues to Expert Tactician, I gain an extra melee attack against you, either before or after my regular action. However, since my regular action has already started, it can't be before... therefore it has to be after.
That first attack is a sneak attack; the other two attacks in my full attack action are not, since you are no longer denied your Dex bonus.
Now my regular action is over, so I take the extra attack granted to me by Expert Tactician... but since you're no longer denied your Dex bonus, it's not a sneak attack.
Likewise, if I'm using an invisibility spell, and I walk up to you and stab you, you're denied your Dex bonus, which means I get an extra attack from ET... but since the spell ends with that first attack, you're no longer denied your Dex bonus when the ET attack occurs, so it's not a sneak attack.
-Hyp.