RTD quests also introduce you to the concept of Exploration of the Dungeons. Let's start with quoting the developer team on the concept of 9dragons dungeons :

There were also some evil groups who were bent on acquiring wealth at the expense of others. These monster clans had many followers. Often, they also had highly defensible headquarters, and sometimes, these were in strange dungeons. They also had lots of gold plus some very interesting articles and magical weaponry.
In 9Dragons, nine of these dungeons exist for your adventuring pleasure... well, it may not be such a pleasure when you find out what awaits you there.
How do these dungeons work? Firstly, you and your party need to open each one up. But be warned, the monsters in the dungeon are usually 10 to 30 levels higher than the ones outside. You'd better be plenty tough.
The missions themselves are timed. Depending on the dungeon you enter, you get either 20 or 30 minutes to fight your way through. Once you enter this darker place, you and your party are on your own. No one else can enter that space to help you while you are in there - even if you are getting your little martial artist **** kicked.
So what is there to go and find? Well, for example there is the Judgement of Hell (big drum roll in the background please). This is the home of the leaders of the monster clan from the Valley of Hell. Now, it is said that the Valley got its name because a power hungry lunatic by the name of Mei San-He used human bodies in his demonic experiments trying to create an army for himself. The scary thing is that he mostly succeeded. The valley itself is full of zombies and undead who dearly love to rip any living thing to pieces. Then, in the dungeon itself...

In 9Dragons we have the following levels of dungeons :

Purple Pass- Very easy, beginner level dungeon.

Superior Pass (from purple to black) - Middle levels dungeons with levels from easy to hard .

Green and Red Pass - Revamp dungeons, hard level, high level dungeons.

Each level/pass of dudgeon have different items and rewards. Some items from those dungeons can't be traded and stay only on holder (player character). If you kill the boss of the dudgeon you get a killer epithet and if you exit the dungeons you get conquer epithet. Superior dungeons had other type of epithet, but at some point in game they got bugged and could not run them/ take the quests/ combine the items for epithets.

You can explore the content for items of the dungeons in F11 meniu / Resource or Craft. Some items from the dungeons can be picked up and are under resource and some can be crafted from mats but can fail upon craft and are under Resource meniu.

In the quest line of RTD you have to quests which send you to COF (Choice of Fate) and VOH (Valley of Hell or Judgment of Hell). You get 3 purple passes. It is better to use the passes to make the entire runs and get also epithets, among other items.

COF :

VOH :

Dungeons in 9Dragons

Hefei Map :

The Training Dungeon (available at events) level 20.

Zhengzhou Map / Shi Zhang Map :

COF (The Choice of Fate) purple

COF (The Choice of Fate) Superior

Jinan Map / Datong Map :

VOH (The Judgement of Hell ) purple

VOH (The Judgement of Hell) Superior

Bloody Plain / Cave of the Conqueror Map :

CCD (The Cave of The Conqueror) purple to black

TGW Cave : available only after black vs white war for the clan winner of the war

Nanchang Map :

SCM (Silver Coin Mansion Guide) purple

SCM (Silver Coin Mansion Guide) Superior

Beast Tower Purple

Beast Tower Superior

Hangzhou Map :

Wild Tower purple

Wild Tower Superior

GCM (Mansion of Golden Coin )purple

GCM (Mansion of Golden Coin) Superior

Liaodong Map :

SRS (School of Rising Sun ) purple

SRS (School of Rising Sun ) Superior

North Sea Icy Palace Map :

North Sea Icy Palace Dungeon purple

Tibet Map :

KJ (King Jin Dungeon )

The Black Monks Dungeon

Potala Palace

Loulan Map :

East /West Temple Dungeon Loulan (Kylin)

Golden Castle Loulan

Revamp (green & red) dungeons were added many after years of the launch of the game and normal green pass and red pass normal become revamp for level above 120 :

-The Choice of Fate

-The Judgement of Hell

-Silver Coin Mansion

-Beast Tower

-Wild Tower

-Golden Coin Mansion

-The School of Rising Sun

-North Sea Icy Palace Dungeon

-Black Monks (Temple) - (not revamp yet in PapayaPlay version)

-Golden Castle

The most hunted items from this dungeons are :

The beads plates are good start for gear up. Also they increase the experience rate.

The beads plates can be crafted into Bead Plate Heavenly Fist. The success rate is low 2,5 % and you can't use MCG.

Training dungeon Hefei :

COF revamp green & red :

The Death Bead to craft critical ornaments & the plate. Plates : I, II, III, IV & V are possible drops from last form boss. They form COF bead, the relic of COF. raft rate is 100%. If you gather accesorie from the boss can exchange an NPC in front of the dungeons for a box that drops random 1 shard, 50 accessories for 1 box and also 250 for 1 Death Bead.

Weapon Ornaments : can drop or be created using COF and in game resource. Ornaments can fail when are created/ crafted.

VOH revamp green & red :

Plates : I, II, III, IV & V are possible drops from last form boss. They form VOH bead, the relic of VOH. It is 100 % craftable.

Clothes/Deco Ornaments can drop or be created using VOF and in game resource. Ornaments can fail when are created/ crafted.

Regarding craft rate of CONST new ornaments after some tests we got around this numbers , with no MCG only band craft buffs :

20 CONST Ornies have 100 % craft rate.

From 100 (20) CONST we got around +-75-80(25) CONST

From 80 (25) CONST we got around +-12-14(30) CONST

Silver Coin Mansion / Wild Tower revamp green & red :

Plates : I, II, III, IV & V are possible drops from last form of bosses. They form SCM bead, the relic of SCM.

Inner Clothes Warrior & Chi Kung : mobs & bosses drops inner clothes . They can be created from SCM relics & vault of death bead. They have penalty stats - 30 to all attributes and increase critics. They have 6 slots.

Golden Coin Mansion / Beast Tower revamp green & red :

Plates : I, II, III, IV & V are possible drops from last form of bosses. They form GCM bead, the relic of GCM. Plate is 100 % craft.

Clothes & Weapons : mobs & bosses drops clothes that can be upgraded in superior ones They can be created from level 1 to epic using in GCM resource and GCM beads. It is 100 % craft if you use double dragon spirit.

Deco : Gale Yellow Dragon Elite Costume . The new deco that drops in GCM (F &M ) have 2 levels, level 1 and level 2. From level 1 can be upgraded to level 2 using collectibles from inside of GCM. It is 100 % craft if you use double dragon spirit, if not can fail.

The extra decos drops can be used as fabrics in costume gallery to unlock new slots for extra ability.

As extra note, the main loot room in GCM contain Gold Coins Chest of the Overlord. The key of this chest drops from bosses in Beast Tower. The key is rare drop.The chest contains items like Sales Pocket (100 million), Bead Plate of the Vault of Double Dragons, Banner (Excellence), Rising Bead of Kylin, Five Dragon Banner Box, and Flag of Chaos.