I lost the HH but heres how it went.

Relevant stack sizes, Me, $5000 to start, villain $18,000.

A few limpers, I limp in MP with Kc10c.

Flop Kh 9s 3s. Pot $150

checks to me I bet $80. folds to last guy who call.

Turn Kh 9s 3s 10d. Pot is $310

he checks again, i bet $200 he calls.

River Kh 9s 3s 10d 9h. Pot is $710

Villain leads out for $5,000
Hero?

Easy fold. You're a loser to any 9, pocket 3, QJ or the less likely of pocket K or 10. The villain could have any of these hands, the way you played it.

I would have bet at least the pot or more on the flop to see where I was and to discourage someone from looking for a spade flush. Your hand wasn't that strong to begin with, and you got lucky getting the 10 on the turn. Again, a much higher bet is called for on the turn.

As you played it, unless you have a wicked tell on this player, they most assuredly have you beat.

Bet the pot on the flop.

Bet the turn a little stronger aswell. 3/4th of the pot at least. It's a really drawy board now.

Fold the river, i think he's got a set of 3s here. They make this move a lot when they didn't get enough money in the pot on the flop and turn and then they notice it's a deepstack tourney and they wanna get paid off big time so they just get it allin.

I play it exactly the same, with a fold on the end

We're definately deep enough that we can fold here, but what is villain's thinking with the overbet?
Does he ever get paid off playing the nuts this way?
How often is this a missed flush draw?

he's a donkey probably.