Hypersmurf
Moderatarrrrh...
Opponent fell for feint.
I tried to figure out a way to get Expert Tactician to allow a spell, but it's not coming to me.
Feint is... debatable. It depends on how your DM interprets the wording of the description - similar, I must admit, to using QttE. Both say they deny Dex bonus against "an attack". If it said "your next attack roll" like True Strike, it would be clearer. Ray of Frost has an attack roll, but does it count as "an attack"? I can picture a DM ruling either way.
I think a Chill Touch already in effect would work, in any case.
Expert Tactitian, however, is a red herring. It doesn't deny your opponent his Dex bonus... it simply functions against an opponent who is already denied his Dex bonus. And in some cases, your attack from ET is against the full AC: for example, if you Feint, the opponent is denied his Dex against your next attack. Not every attack that round, just one. When you go to make that attack, because your opponent is denied his Dex bonus, ET kicks in, and you get an extra attack... but since it's not the one you feinted for, he gets his Dex bonus against it.
Again, I'd let someone use a precast Chill Touch on an ET attack.
-Hyp.