5T seven handed live. Effective stacks 150 bbs.
I am in +1 and bring it in 3 bbs with Qd Qs playing my 2nd hand at the 6 handed table. 2 callers: hijack and reg V on button.

the flop cames Ad Qc Td

and I am beset. I bet 6 bbs and get 2 callers, CO and button V.

Turn is 5d making flush possible;

I bet 20 bbs with my set + 2nd nut fd; V on button calls.

River is blank. I bet 40 bbs, which is pretty committing about 1/3 of my stack.
V goes all-in.

This is the only set (and only one of two combos) that you have that also has a diamond blocker in it. For me, that makes this a call, although you shouldn't be thrilled about the spot.

I would fold as played. Hard to find reasonable bluffs. AxKd would likely 3bet pre from BTN and we block KQo with Kd; I think most people are very unlikely to bluff jam this river without Kd blocker (or at all tbh)

I would check turn. What are we getting value from? What hands are we concerned about denying equity to?

Agree with check call turn

As played fold

Hero calls on river because V only called on turn and V would tend to raise turn to protect most flushes, which are non-nut. But this analysis turned out to be dead wrong.

It can't be right to check with a made hand every time the flush card comes.

Yes but you don't bet turn when you have QdQx

This is way too thin. Like lighting money on fire thin.

I'd check/call the turn. Given that you bet. I would check/call river. Given that you bet the river, I'd definitely fold to the shove. It is highly likely that you are up against a flush. Since it was only a call on the turn, I imagine it was a nut flush that he had.

By the way, you're hand went from 7 handed to 6 handed. Also HJ became CO part way through the hand. It doesn't change anything much, but someone had to say something about it. Turns out that person is me.

V had 89d
how could V not raise turn.

I mean he played it perfectly assuming he had a read you would keep betting for no reason

If an opponent has a strong tendency to continue betting, it can be correct to call with powerful and yet vulnerable hands. Even if those hands are raising hands. It can be better to just call.

I played a HU game against some guy that would always bet the pot IP when it was checked to him. He would bet very large preflop too. I had AA. He bet big and instead of 3-betting, I just called. He bet all streets and was all-in by the river with garbage. Of course all his hands that beat me were playing this way too. However, by not raising I allowed him to put all his money in a high percentage of the time. If I raised at any point he would have folded.

In my opinion, generally, the best strong hands to trap in accordance to vulnerability is as follows:
Full House
Set
Nut flush
Two pair
Flush
Straight

Straights are very dangerous to trap with!

His river jam is bad in a vacuum but clearly good (results orientated probably) vs you if you're capable of b/cing sets.

1. pot control in case a 4th diamond arrives
2. disguising his hand strength