Here's a position for you to sweat over, from a variation that could easily have arisen in a recent game of mine. It's black to play . . .
. . . and defend. Yes, black is a piece for a pawn up - but white has just played 14.f4, threatening 15.e5. What would you play? And why? With what follow-up in mind? At the board I had completely the wrong idea - and my opponent and I fared little better at working out the truth of the position in the postmortem.
See if you can do better.