Here's an interesting hand, one big leak I had is low river aggression fq combined with a low river call efficiency (26/0.95) over a reasonable sample, missing mandatory bluffing spots like this one was costing me some $$, among other leaks obv.
so vilain is unknown, openning 70 otb over 20 hands, he's on auto top up and was sitting alone at the table so we'll go ahead and assume he is a reg. preflop and flop is standard I think, we could argue a flop check raise; at the time of the hand I somehow estimated that check raising and calling flop would have the same EV, so I went with the "meh I call". now that I think about it check raising can't be bad since we don't get 3bet that often, considering flop texture. people just 3bet so rarely on these kind of flops with their entire range; trapping with monsters since there is little need for protection, and one pair type of hands aren't just going nuts without any reads. so yeah we get to realise our equity on the turn like every single time when we check raise, and we get to cooler him more often then he does when we hit ♦, so I think check raising could be slightly better.
he capped his range with the turn check (pure assumption obv, but we'll have to go with it) so this is one of the spots where I miss alot of $$$ while on autopilot. he bets kinda big on the river, we have no idea on his bluffing freq so we will assume he is somewhat balanced here. top of his value range is 33 that he decided to cbet flop with (he has 100 cbet 2/2 so what do we know he could have it) higher sets are not checking back that turn, A3/J3 and maybe some combos of 83 or J8 he decided to x back for some reason, he will probably have every Ax up AT, maybe some AK combos and that's it. that's roughly 125 combo, and he needs 42% on his bluffs to break even, that's like 53 bluff combos to make us indifferent (not sure about the math though, I'm not a gto guru or anythings to be clear haha).
Theory and rational thinking a part, by experience this is mostly a situation where he is going to show us Ax like always with this line and bet sizings, basically it's a "hunch" but let's call it a population read thing 
on the other hand, when we check raise we have a stronger percieved value range, in the sense that he can't discount KT,T9, 88, A8,A3, 33 ( most those crush his value range) from our range even if the most standard line is to lead river. Some of those combos might not be in my range, but since we are basically unknown here, most regs expect to see the nuts more often than not when facing a wierd check raise on the river, therefore I expect to get plenty of fold from his value range, too lazy to do any more math now, but I will look it up later haha 
add to that, what could we bluffing with a part from a pair turned into a bluff, or an oop float that decided to play wierdly and check raise on the river?? one of the only bluffs that makes sense to an observant player is our exact hand along with some combos of 8x 22-66; and all those are pairs turned into a bluff, I assumed that he is an abc solid reg and won't be outlevelling himself readless, most abc solid regs don't expect others to start turning pairs into bluffs early on a hu match, it's like a population tendancy imo, that's what most abc winning regs believe in. so putting ourselves in vilain's shoes, our bluffing range is so narrow, while he cannot discount some nutted combos that are trying to play funky to get more value, making him hate life with A7 or whatever he probably had
plus we have the J blocker to some J3 combos that he might bet and then decide it's exploitable to fold, and go on "lolgtoIcall" mode. Minor blocker effect obv but it should count as an argument for turning our exact hand into a bluff.
so to sum it up, vilain is capped, we have some nutted hands in our range when we check raise river, and we assume that he will overfold too many value combos, I think this makes it a mandatory bluff, even if we get called we'll have a monkey image, wich can't be bad long term too
Hand Information
No Limit, 2 BB (2 handed).
Hand History converter courtesy of pokerhandreplays.com
Table Information
Seat: 1 Player 1 ($200) Dealer
Seat: 6 Hero ($200) Small Blind
Dealt to Hero
T♦: J♣:
Preflop (Pot:3)
Player 1 RAISE $4
Hero CALL $2
Flop(Pot: $9)
A♥: Q♠: 8♣:
Hero CHECK
Player 1 BET $6
Hero CALL $6
Turn(Pot: $21)
A♥: Q♠: 8♣: J♦:
Hero CHECK
Player 1 CHECK
River(Pot: $21)
A♥: Q♠: 8♣: J♦: 3♥:
Hero CHECK
Player 1 BET $15
Hero RAISE $59
Player 1 FOLD
Showdown:
Hero MUCKS
Hero wins the pot: $95
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