As a player, I was a half-dragon monk, level 6 or so total, which meant that I had 3 levels and none too many hit points, nor especially good saves and skills and such. I was playing in a solo game, and I was in a dungeon looking for a dragon who might know where my father lived.
Towards the entrance of the dungeon, I spotted a rotting corpse that was impaled against the wall. Not having any skill with finding or disarming traps, I instead deduced that he stepped on some sort of trap and paid for it. I spider climbed over the vicinity of the corpse and continued. The place seemed empty, until I saw a troll sleeping in the hall. Long story short, I wasn't able to sneak past it, and it woke up and started chasing me. I knew that I had zero chance to kill a troll by myself, since I was a pretty poor fighter with low AC and hit points, let alone the fact that my only fire was my breath weapon. The only thing I had was a good base speed. So I ran my little behind back to the area with the trap, and made a leap to the place that I knew was safe. The dumb troll followed me, walked straight into a VERY lethal spear trap, and I used my ready action to breathe on him and get him negative, whereupon I lit a torch and coup de grace'd him.
I was awfully proud to beat that thing using just my wits.