I like your line. On the turn I also like the idea of overbetting. You can balance it with Jc9c, Tc9c, JcTc. On the river I also like the block bet, but you have to be a bit careful, because you have to have a calling range once he shoves. So you can´t do it only with hands you end up folding.

However practically I would not block this specific river, since I assume it is underbluffed in your games.
Do you think villain will turn any Ax into a bluff? No. Do you think he calls two big bets with a gutter? No. So he clearly has an Ace or a big draw.
And also people tend to overfold once the third spade hits so imo he is not calling the river 1$ bet with most of his Aces (he would have raised two pair on the flop 99%)
--> If you check and he bets he has it 95% of the time in my opinion.

Why do you think 25/13 is bad play in that amount of hands. With that amount of hands there is no way telling if he has a big VPIP/PFR gap only thing I see a VPIP of 25 which is not to tight and certainly not to loose. Ony indication is hes not auto stacking up his stack (h'mm might need to try that and play like a NIT and get called and raised by everyone as I seem like a fish).

Given the stack sizes and the level a turn over bet followed by an allin on the river might indeed be a good idea as people tend to let not go of e.g. AK or AJ on this situation.

I am not a fan of block bets but given the stack sizes I can see merit in a thin value bet on this river to get calls from Ax hands but would normally make it a bit bigger value bet but stack sizes are to odd to do this.

Given the odds (~27% needed I guess) I could make the call to many people could either make this play with AK and even AJ or with a missed JTs hand (straight draw) because of the bet sizing you chose and try to wheel you in with a worse A. Don't think that the EV difference is big though between calling or folding that is the main reason I would tend to call and get more info about the villain.

Interesting spot.

Check/raise flop. I think this board is better for BU and he also has a lot of draws that he might bet/fold. Overbet turn if he checks back. Balance with combo draws and maybe some 8x.

Rest of the hand is good as long as you also have flushes in your range OTR with that betsize.

I agree with Resolve that check/raise flop is better. You're gunna put a lot of Ax in a bunch of shitty situations on a lot of runouts and also get a bet out of some air occasionally.

I think your river line is likely a little face-up honestly. You're saying 'I think you'll pay my two pair hands with an Ax and let me get away for cheap when you have a flush because you'll never bluff shove'. If that statement is true then the block bet is great if it isn't then the block bet is tragic.

(And for the record I think it probably is true at 5nlz more often than not.)

The question is, what is this guy flatting/3 betting vs. this open OTB? If he 3b a reasonable "value" range, his best A here is AQo (and that might be a stretch). Sample is noting, but he is trending in the opposite direction of the 75/5 guys you see after 25 hands. I have to assume he has a bunch of A9s-A2s, possible A8o, but that doesn't seem likely. He has 2 sets (if he doesn't 3b QQ). He has a bunch of Gutter+FD's. He has 3 not so great OESD's and 1 great one (JTss).

It's reasonable to assume his continue range on flop is all combo draws and TP+. You are slightly ahead vs. his calling range. Turn, I think it is reasonable to assume he continues with all combo draws and he dumps all but two pair+ (maybe some weird call like AxJs with blocking effect). River is tough since he just doesn't get here with anything weak. My logic would be that he has next to zero combos in his range here that you beat so betting here doesn't make much sense. I can maybe get behind a block with A8, but I think AQ is better. Then, there are two pair combos that might call. I think you could also potentially block bet with like AsKx, AxKs since you would block a bunch of flushes and also be able to get better hands to fold but this might be a stretch.

I think you should probably check/evaluate this river and only block the non 9, K & spade cards. Mostly have to fold to all but the smallest of bets after his range has been condensed down to such a strong range.

This approach works vs both fish and reasonable players (with your Q8, the block is good with better 2 pair). You get two streets of thin value, but it is value, against the reg. playing his combo draws passively vs your huge bets. You exploit him by checking spade, K and 9 rivers. Sometimes he checks back 1 pair hands and you win at showdown, rest of the time he ships and you already know what he has. You can then block non spade rivers and bricks and potentially get value from AJ, A9.

And vs the fish, you get two streets of fat value vs. his A3, A9, AJo. He will have the same draws as the reg. but his overall range is going to be wider here. You can check/evaluate all K, 9 and spade rivers (I will probably be calling some stupid 1/5 pot bet here or some weird size) and potentially block this combo on all other bricks.

I will also say, I think there are a couple other lines and/or bet sizings we can consider here

My two cents. This is good idea to check raise on the flop, but i would do it only if we have information that villain will bet after our check, also I like your idea to overbet he can call you with Ax and FD. Like was said above you can balance here but I don't think that it's good idea vs fish. If you play vs fish forget about balance, just play exploit poker.