I'll do a run down of the party.
Attitcus Aldritch, human wizard
Voldun Kreishnetch, elf ranged fighter
Tianchi, aasymar monk (Tianchi also had a NPC dragonborn companion named Mei)
Kikuchiyo, warforged fighter (basically the character from the Samurai 7 anime)
At this point in the campagn the group is aiding the True King of Esterlain against the usurper king, working to stop the evil king's evlish genocide. While the King's armies battle on the front lines the group is sent far north, deep into enemy territory, where an enclave of Drow have been hold up within a fey forest, surrounded by enemy troops. The King's plan is to send the group in aboard the Cloud Scier, a small and fast airship that can drop them and a teleportation device that will allow the king to open a second front in the far north. (My campagn was a somewhat steam punk setting, airships were just becoming a thing)
But the group successfully crash lands within the enemy encirclement and link up with the Drow. They use the device to set a teleportation circle to warp in reinforcements and several heavy siege guns! The Drow had been held up in this forest for almost 10 years, long before the war had started, and since the enemy couldn't enter the forest without being torn to shreds by its tree-kin guardians they built a fortress around it instead.
The Drow general was glad to see the heavy siege guns, they would be the perfect weapon to crack the enemy fortifications. The problem was the teleportation circle was temporary, and faded quicker than expected, the soldiers were unable to bring enough ammunition for the big guns to sustain a heavy barage. The guns would need marked targets to ensure enough of the fort was destroyed to make taking it possible for the small force within the forest.
The officer in charge of the siege guns had a plan B. He gave the party, what looked like, several large coins. Each "coin" was actually a marker that would feed targeting information back to the crews so they could fire with pin-point accuracy! All the group had to do was infiltrate the heavily guarded fortress and place each marker at key points.
So I had planned the group to try and sneak in, they'd mess up at some point, and they'd have to fight their way through to get the markers placed. It would have taken us atleast 2 sessions to get through this. But NOO!!!
The Wizard, a man named Atticus, had to go and ruin everything! He suddenly realized he had the spell Animal Shapes, which let's you turn yourself and any willing creature into an animal. He said, "I can turn us all into birds and we can just drop the markers!" The astute wizard even thought to ask one of the Drow what the most common bird was in this area!
I never want to trample the enginuity of my players so I ran with it! Atticus turned the party into a small flock of golden peasant finches, the most common bird to Northern Esterlain, and they were able to easily scout the frotress and marker its more vulerable parts. They then postioned themselves, ready to charge in ahead of the infantry after the guns fired. The fortress fell with minimum casualties to their side!
The group then used this same strategy to take the next two cities. They even made sure no one ever saw them turn into birds so there was no chance the enemy would catch wind of their cheesy tactic! It was the most frustrastingly beautiful thing I've experienced since I started DnD. Ive got a great group! Love those guys!