So, a while back, I was DM'ing a campaign for my dad and brother. My dad was playing a Fallen Aasimar rogue/fighter, and my brother was a Tabaxi Gunslinger. Recently, they had come into the kingdom of Skyfell, ruled over by the Dragon King Amnarath. After some exploring, they decided to go to a brawling ring known as the "Brawler's Den." The Tabaxi, Crescent Moon, goes in and gets completely destroyed by a halfling monk. The Aasimar, Crade, decided to go in and try to avenge him. That didn't go so well, and after several minutes, Moon and Crade drag themselves out of there, damaged and hurting.
Crade decides to go and find an inn for the night, and Moon agrees. After they rest up and recover, Moon wants to go and find some coin. Crade agrees, and after some searching, find a bounty board. It's essentially a wood board with various bounty tasks on it. So far, nothing seems to interest them, so Crade goes to investigate a nearby man with an eyepatch smoking a pipe watching people come and go. As he does, Moon finds a curious slip of parchment. It's old and frayed along the edges, giving Moon the hint that no one wants to complete that bounty, even with the 150 gold reward. The parchment says the following:
To anyone with sizeable strength and courage. Go to the Undercity (the underbelly of Skyfell) and clear out all Fleshwalkers. 150 gold reward to anyone that comes back with proof of the completed task.
By now, Crade has successfully struck up a conversation with this mysterious man. He introduces himself as Charon, a business and ferryman for the Undercity. He transports people and goods via shortcuts dispersed throughout the Undercity, hiring guards along the way. Moon, Crade, and Charon talk for a bit about this bounty, and Charon agrees to help them track down one of these monsters.
The party continues down the street until they come upon an arched bronze gate roughly 20 feet high and guarded by two Dragonborn guards. Charon shows them his pendant that gives him access to the Undercity. The sentries give them the go-ahead and open the gates, closing it behind them. Almost immediately, a group of Manes attacks, but considering they have the HP of a goldfish, Crade and Moon curb-stomp them and move on. Charon has them board his boat, and off they go.
I describe the Undercity as having a very eerie and ominous feel, with odd noises and shapes coming from the shadows and the water. A set of fins breaks the surface of the water, curling up for a moment before disappearing under the surface once more.
Several in-game minutes later, the party hears a sound. It's a cross between a ghostly moan and deathly breathing. Since both Crade and Moon have darkvision, they spot something striding slowly across the damp stones and soil.
Now, this is where I reveal my Homebrew monster, called a Fleshwalker. It's tall, easily ten or more feet, with long arms dangling past its knees. Everything about the monster is thin, almost skeletal. Its hands end in wicked claws, but the scariest thing is the Fleshwalker's face. The creature has no eyes or hair, yet it's bloody mouth is bristling with sharp scraggly teeth. Bits of crimson flesh dangle from its fangs.
Crade and Moon jump off the boat a ways away and set up to get ready to bring this thing down. Moon fires off with his giant rifle, scoring a hit. He rolls a 12 and a 10, which is massive damage off the bat. Crade criticals with his enchanted longbow, doing an extra heaping of dice and loading on the damage, then multiplies it by 2. 67 damage before initiative even starts.
I'm dumbfounded. That was nearly half its hit points gone already, and I don't doubt this thing is going to go down quickly when things get ugly. I narrate the creature screaming in pain as the magic arrow and bullet find their marks on its body. It turns, using its Blindsight to locate the two attackers, and then strides to meet them, claws flexing in anticipation of the following bloodshed.