Last night only half of the players were able to make it. So, instead of continuing the main quest, I ran a side quest for the players.
- Human College of Valor Bard
- Half-Orc Berzerker Barbarian
- Changling Way of the Shadow Monk
To catch you up to speed, the players are in a Dwarven mining town, so that one of the players can hope to buy a rare, precious metal, and their cart is being upgraded (ballista turret on the top, and steel axles, it's going to take a few days).
So the party has a few days to kill, which led me to make some time for a side quest.
An old Wizard Dwarf with a Sean Connery voice approached some of the party with a request. He asked if they were able to travel through an inter dimentional portal to another world to steal back artifcats that some mysterious figure has been stealing from him. He would go himself but the portal is only one way and it closes once the figure goes back inside to it's home world.
In return he offers them an artifact from his collecting for each of them (nothing too crazy or strong, just another magical item, with quarky properties). All they have to do is chase or follow the creature into it's portal as it leaves, but they have to hide so they don't scare it away prematurely.
The Dwarf also has to soul tether to the party, which is a magical process of tethering their souls to his soul, so that he can pull them from the other world back into their world. Because of the soul tether, they can also get his detect magical items sight, which his artifacts have a neon glow with a purple outline.
Anyway, the Dwarf turns them invisible, they wait in the room until midnight, the portal opens, a large humanoid steps out of it. It wears rags, has long clawed hands, and it's eyes glow a menacing green. The creature steals a chandiler, a banquet table of infinite feasting, a magical book and a crown. Now the players must retrieve 28 artifacts!
The party goes through the portal, which makes a lightning sound everytime somebody enters that isn't the maker of the portal. This alerts the creature, who goes back through and abandons stealing anything else.
The creature and the party members arrive on the other side of the portal, in the other world. The creature knows it's being followed, so it turns invisible and runs off toward it's lair. Luckily, the party notices footprints in the sand it left behind.
So, the world they arrive in is mainly comprised of a giant, black rock. There is sand but it's purple. The air is arid and warm. A tree grows from the sand, it's bark red and it's leaves yellow. Another tree grows as well, with the same red bark, but it's leaves are large like aloe vera leaves, and it grows orange spiky fruit with red spots. The party collects a bit of all this strange stuff to transport back to their home world.
They follow the foot steps, when they realize they abruptly end. So they look up, see a chain hanging 10 feet up from the ground that leads up to a floating island. They climb the chain, make it up to the floating island. The island is made of ebon bricks, there is a rainbow colored lawn, the dirt is purple, and what looks like a big, black, thorny tree in the center.
They see the figure they've been chasing run into a door on the thorny tree, after it enters, 4 more branches come up off of the tree. They go to the thorny tree, read an arcane incantation and cast Knock, the portal opens, and they fall inside into the basement.
The players fall down into a basement, where they are greeted by 6 Spectators. The Spectators all take turns talking to the players telepathically, sometimes taking over a sentence where the last one left off. It tells the players to leave, it warns that they will eat them if they don't, they want their souls but only if the players don't leave.
The players don't know how to leave, so they decide to stay and fight. They are getting owned pretty badly by the Spectators, when the Monk decides to cast Darkness in the room, which the AoE of the spell fills the entire room. This casting of Darkness prevents the Spectators from using their eye laser abilities. So the players fumble around the dark, attacking at Disadvantage on the Spectators, until there are only 2 left, so the Monk dispels the Darkness and they finish them off.
6 beams pop up from the floor, one in each spot where a Spectator died. They players use the beams, heal 1d8+2 and go up to another floor. This time they are transported into a room with 4 doors, 1 normal sized green door, 3 tiny doors which are red, blue, and yellow. Each door has a one-shot veil of magic in it's portal, so when a player passes, they suffer the effect. (they can throw something through the doorway and it would effect whatever they threw, but they haven't done that at all).
So the Half-Orc goes through the green door, heals 1d6+2, finds himself in a room full of potions and a chest. Goes to the chest, finds one of the artifacts, grabs it. The room starts to quake violently and shrink rapidly. The potions falling off of the shelves, shattering as they hit the ground, the Half-Orc runs the hell out of there. As he goes back into the main chamber, the green door disappears.
The players discover when you take an artifact, the room starts to disappear. They go to other rooms, avoiding the magic veil by Misty Stepping for the Monk. They collect all the artifacts that they can on this floor, each of the previous rooms disappearing. Until there are no more rooms left and 3 portals open. Each player goes into a portal, heals 1d8+2, and they wind up in another room, 1 normal sized green door and 3 tiny doors, purple, pink, and orange.
They semi find out that when you bring an artifact from the floor you are on near the tiny doors, they grow big and allow access. They find this out by finding the Banquet Table of Infinite Feasting, which shows you several of your favorite food and drinks on the table. Well, they would grab the food and moosh it into a door and it would grow.
They cleared that floor and 3 more beams arrived. So, they go through the beams, heal 1d8+2 damage and go up to the third floor. Again, 1 normal sized green door and 3 tiny doors, white, black, and brown. They go through the green door, into what appears to be the creature's bedroom, they find 3 artifacts, the Chandiler, an Outfit, and a Flute.
So the party left off there on it's side quest. Hopefully we can finish their side quest before the whole main group gets together. Boy will they have a lot of explaining to do when they get back, if they get back 
On a second night they continue their journey. They still have no idea bringing an artifact up to the small doors that they picked up from their current floor makes the door grow.
And so they go through the white door, the Half-Orc blinded. The room is filled with 4 jail cells, ghasts in each cell. The players go in, the door slams shut behind them, the jail cells open. The ghasts come out, fighting, clawing, biting, etc... The Half-Orc takes massive damage, almost dies, the Monk saves the day. When a ghast dies, it crumbles into an artifact.
So then the Monk decides to go through the black door, to find a pool room, with four topless ladies inside, and two couches lounged in the back. He likes the idea, walks forward and slowly dips a toe into the pool, to have it corrode off because the pool was actually acid! Then the ladies turn into their demon form and beckon him forward, so he uncontrollably walks towards the pool of acid, but first, he lathers himself up with the bar of artifact soap. Dammit! How did he know? The lather of the soap protected him from the acid!
The other players realizing the Monk is in parel run inside. The Bard opening the book of 365 Godly Sex Positions: 1 For Each Day of the Year, this seduces 3 of the 4 demon ladies, who get on the couch and get ready for a good time. So the Monk is battling the 1 remaining demon lady in the acid pool, who eventually turns into her ethereal form, which now the Monk is unable to hit. The Half-Orc starts pointing the artifact which is a Golden Hand with a finger pointing on a Golden Rod, it shoots Lightning Bolts, Magic Missile, until he decides to throw his Handaxe of Returning +2.
The Bard is off pleasuring the demon ladies, stabs one in a sneak attack, they all go to turn on him, he lies his way out of it, passes the roll. The whole party laughs, the DM laughs and shakes his head. The ghost demon lady dies while over the acid bath, the artifact falls towards the acid, the Half-Orc catches it, which causes the room to shake and implode. The players grab an artifact one of the demon ladies gave up from being pleasured well, then flee like hell. They loose out on two of the artifacts.
They then go through the brown door, which is a giant dark room, filled with refuse waist high on the floor below. The only character "brave" or stupid enough to wade through it is the Half-Orc, who uses his feet to Investigate. So I have him Investigate square by square, and roll a Con save at the same time. A failed Con save equals 1d4 points of Poison damage. After finding 5 of the 6 artifacts in the brown room, and only having 4 of 16 squares left to investigate, the Monk decides to use the artifact Chamber Pot, which swallows refuse into an infinite empty void, thus clearing up the room.
So the party collects all 6 artifacts in that room, a giant beam opens in the center of the room, the party goes through, each member heals 1d20 HP.
The level 5 party of 3 winds up in a room with a CR 7 Oni, who is the mysterious figure responsible for stealing the magic Dwarf's artifcats to begin with. They battle, ultimately winning and narrowly escaping the artifact dungeon. Then the magic Dwarf with the Sean Connery voice uses the soul tether to bring the characters back through to their world. For a job well done, he rewards them with three minor artifacts, found here, http://community.wizards.com/forum/product-and-general-dd-discussions/threads/4242741