I was DMing for a my group of rag tag dumbasses doing our usual homebrew campaign. I decided to give them a puzzle instead of having 3 level 6 PCs fight an ancient red dragon. The puzzle was in the form of a riddle that required them to find and kill 3 different enemies. 1st was a group of orcs, 2nd was some bandits and 3rd was 2 giants. Since the sun was going down they didnt have a lot of time to kill these creatures, so our paladin had the best idea ever. Make them kill each other. She ask the dragon where the ors were and by stipping down to her comon clothes and throwing a javelin with a nat 20 to hit, she speared an orc in the head and got the rest to chase her as she led them into the bandit camp that our rogue had found while scouting. After getting the orcs to chase her into a forest she then threw and alchemist's fire on them. The bandits shat themselves as they was these orcs run at them covered in fire, so the bandits then started fighting them. All this commotion alerted the giants who on arrival started smooshing bandits and chard orcs. Then after all the bandits and orcs were dead the paladin and warlock decked the two giants who were quite wounded. Needless to say the dragon was impressed.

TL:DR badass paladin makes orcs bandits and giants fight each other to solve a dragons murder riddle