8♠7♠ CO vs BB, turn on Q♠ 9♦ 4♣ 2♠, 70 bb

Best play: Call

Why

The 2♠ turn brings in a spade flush draw and keeps the board dynamic, but it's a blank for top-pair value, so the bettor's range is still bluff-heavy. Your 8♠7♠ has no pair but a strong combo draw: the second-nut spade flush draw (8♠ 7♠ with Q♠ 2♠ on board) plus an open-ended straight draw around the 9 (a T or 6 makes the straight). In position facing the turn bet, calling is best: with ~15 clean outs you're getting a price to continue, you keep the pot manageable, and you realize your equity with position rather than turning a draw into a bloated bluff-raise.

Key idea

A fat combo draw in position is usually a call: you get a price, control the pot, and realize equity without committing.

Common mistake

Raising this draw into a likely bluff-heavy range just blows up the pot and folds out the worse hands you dominate.