Q♠J♠ CO vs BB, river on K♠ T♥ 7♠ 6♣ 2♠, 90 bb

Best play: Bet 40% pot

Why

River, board K-spade T-heart 7-spade 6-club 2-spade. The BB is capped here, while as the in-position CO you hold the top of the range. With Q-spade J-spade you have made a flush: three spades on the board plus your two give you a K‑Q‑J-high spade flush, beaten only by an ace-high spade flush which the capped BB almost never has. A 40% bet is the thin, merged value size that gets called by the BB worse made hands (two pair, sets, worse flushes, stubborn top pair) without isolating only the rare nut flush.

Key idea

When three of one suit hit the board and you hold two of that suit, count the flush before anything else — a Q-high spade flush is value, not a high card. Versus a capped range a small thin-value size keeps worse made hands in.

Common mistake

Misreading Q-spade J-spade as merely queen-high and checking back, or overbetting a non-nut flush and only getting called by the better flushes you cannot beat.