10-handed local 2/5 game.Max buy in is 240BB.Effective stack is $1.2k. Villian is a lag bad player who often chases draws and stabs at pots given chances. Hero just sat down in this loose game. Previous last hand history(BT straddle on,hero raises $40 KdQd in bb,bets $100 on flop 4 way pot , $200 turn and checks blank river on KhJhTc7c2d board.Villian flat calls and check back with Ah7h flush draw+pair). Now immediate next hand,BT straddle on,hero raises $40 with AdQh in sb. Vllian in MP calls, two other callers behind.
Flop($150):As Ks 7d hero bets $100,only villian calls.
Turn($350): 3h hero bets $200 again,villian reluctantly calls.
river($750): 5s. hero checks, villian bets $500. Hero ?
Should I just bet $200 to block his big bet?

According to your reads just fold, you don't even have the Ah

Sigh fold. More money on the turn, per your read of this player. If he is going to go for the suck out, overcharge him.

I personally wouldn't bet on the river, but it seems table dependent.

That's a tough one. Reading the post, it's a fold, but why so big?

I'd need some live tells, such as how fast did he call flop? How fast did he bet river? Did you get any other read?

What hand do you think he can have by the river that you beat? In the prior hand example he checked back river with a middling hand, you also say he likes to chase draws. Well, the draw came in and he didn't check back. I think this is a pretty easy fold.

Fast call and bet.he also said you got it last time. How about a river block bet vs these loose sticky guys?

I'm just wondering if we should make a block river bet. He is also sticky post.

My problem with a blocking bet is that it looks exactly like what it is. It is so incredibly unlikely that you have a flush, but much more likely that he does. If he won't bluff your blocking bet, go for it, but if he's any good, he'll raise it.

However, you do say he's bad and will stab at pots, but he's sticky and will chase -- and his actions look like a flush. Tricky river spot.