Scout the camp, then attack

As far as you know no one died from being to cautious so instead of just going for it you decide to check the camp and its surrounding for traps or other unpleasant surprises first. Flying in big circles above it you notice a few things: first there are five tents instead of 2 tents which makes you extra cautious since that would mean that there are a total of 5 heroes instead of 2, secondly the branches of a big tree near the clearing move irregularly, even when there is no wind you see them move now and then, maybe hiding the presence of one of the "missing" heroes. Lastly the 2 figured by the campfire, a male dwarf and a female gnome seem really close, they sit tightly together and hold each others hand throughout their conversation, if you are to take these two out they will need to go down together.

the first thing you want to check out is the moving tree you think, it would be unsafe(to say the least) to leave a potential threat unattended. Riding a wind current you glide closer, making sure not to make a sound until you can look between branches. There on a thick branch you spot a male elf wearing dark green clothes, blending pretty well with his surroundings. His bow in one hand his other hand lightly on the string giving him the appearance of someone ready for trouble where it not for the fact that he seems to be dozing off a little, with this in your mind you glide away from the tree, riding an air current up until you are back where you started.

Keeping an eye on the elf you try to spot the other missing members of the party, when the wind blows trough the campsite and makes the tents shiver a little you spot them, one blonde woman, human by her facial features. If you saw that right she is sleeping in her armor (the highest grade armor in her party the voice in your head chimes in), "she must be the leader of this party" you mumble. The last one's face was hidden by his tent but that didn't matter to you since you saw something better. The last hero was wounded, they had bandaged his leg but even as you looked you could see blood seeping trough it, "easy prey" you grin.

Thinking of a plan to take out one of them another idea comes to mind, your master wants you to show him how capable you are? Then you will show him just that! Quickly revising your separate plans into one plan. With a bit of luck and a bit of skill you might actually have a shot at this. You run over the plan in your head one last time, then you go for it.

Taking your first arrow and setting it to the bowstring you aim at the slumbering elf, floating towards his hiding spot once more until you got him clear in your sight. With a soft whining noise the arrow is released, traveling trough the air until it meets the other archers throat. "chck" the arrow bores trough the elves neck impaling him to the tree he was sleeping in. One down, 4 to go.

Reaching into the pouch you retrieve the flask of oil, the moment the wind blows trough the camp and the dwarf and gnome scoot a bit closer to the fire you trow it down, right into the fire. "You better be right about this oil" you think to that little voice in your head. And right he was! The moment the flask shatters the oil causes an explosion sending flames everywhere and knocking the two lovers back. The stench of burning hair fills your nose as you see the two spasm a few times before laying completely still. 3 down, 2 to go.

The leader, woken up by the explosion crawls out of her tent. You ready the claws on your feet and dive down, when she spots you diving down, a silhouette against the light of the moon its to late. your claws leave gushing wounds on her face, not enough to kill her, but with blood in her eyes she will be unable to put up much of a fight.
Landing you swap your bow for your short sword, marveling lightly at the ease of which the bow fits that small pouch before going on with the task at hand. The human raises her war-hammer at you as you come closer. Grinning at her you speak the words. Common uneasier to you then the draconich you spoke to your master but understandable nonetheless: "The overlord sends his regardsssss. Every single one of you sssssshall die here tonight.... Sssay your prayers human ssssscum...." (the voice in your head seems to chuckle, funny your jaws are not made for common, i am surprised you just lisp trough it") The woman shouts a battle cry as she steps forward swinging her war hammer in a horizontal arc. You simply sidestep the attack and bring the hilt of your sword down on her elbow with crushing ****, causing her to scream in pain and drop her weapon. As you stand in front of her you say: "Any lasssst wordssss?" You silently admire her resolve when instead of speaking she spits in your face, not so much that you spare her, but admire her still. With one swing of your sword she falls to the floor, blood dripping from her throat as the light in her eyes dies out. 4 down 1 to go.

Casually strolling towards the last hero you look around the campsite, one of the tents is smoldering lightly because it stood to close to the fire when the explosion occurred, the dwarf and gnome lay side by side embers in their hair, at the bottom of a certain tree a small puddle of blood is forming and just behind you lays the slain corpse of the party leader, time to finish the job. Upon reaching the last tent you look inside, seeing a somewhat older elf on the ground, feverishly moving his eyes under his closed eyelids. You might be a minion, inherently evil, you are not unnecessarily cruel, you extend the claws of your left hand and put him out of his misery.
5 down 0 to go.

Walking towards the middle of the camp looking around at your handiwork. Putting your sword and quiver into the pouch you start laughing, a chuckle at first soon growing into a low roaring laugh. Kill one of them your master ordered, well that definitely worked.