My bad, I did leave out flushes, although its very few combos. QTs, 78s, 67s, 54s. Away from my computer but those combos will only move the equities a little.

I think the biggest thing is his river sizing. That's sizing lowers the chance he has a very strong hand. AQ would totally bet here sometimes given how small the pot is.

I think a good spot to merge is a) against someone who is suspicious and like to call you down because if either history or their tendencies b) where you are likely to have a bunch of missed draws in your range

So something like: you raise to 4bb in CO with AQdd, villain calls on the button. Board is Qs9s7h. You bet 6bb, he calls. Turn is 2d. You bet 15bbs, he calls. River is 3h. You bet 55bbs. Suspicious villain thinks you are polarized and have many busted draws in your range and that you would bet Qx smaller on the river if at all, so he calls with QK/QJ/etc. Obviously it should be against the right player with the right dynamic. Ideally he would have caught you bluffing earlier in a similar situation.

@OP: I think this was a meh spot to merge at best.

The obvious other requirement would be that villain has to have a marginally worse hand than yours to call with.

I disagree with ranges people cited where AQ and AK is in the set. GIVEN that opponent is good and bet three streets OOP on a monotone AJx board, you aren't beating anything but air. IMO his range is extremely polarized here, so you can't merge here.

Yep.