Hello, I know there is already a Razador run, but I made one myself, being more specific about what you actually should and shouldn't do.
Razador can be entered at lvl 100 but you need a groupleader that is 104+. Also, don't forget to buy a passage ticket at the general store, because else you won't be able to enter. I would buy alot of them, since they don't cost that much. To hit more against Razador, there isn't a specific bonus, but % monster and average damage always help. However, it's recommended to get as much devil as possible, since the mobs in Razador run are all devil except for Razador himself.
When you enter the run, you have to click the statue in the middle, after doing this you opened the first room, and you will have to clear all mobs. (Make sure you cleared them all, use capes at the walls, some of them might be stuck in it). After you cleared first room, you have to go the statue again, and open the 2nd room. In this room you have to kill mobs untill you find a "golden cog wheel". If you found one, you have to drag it on the seal in the middle of the room. If it's the wrong key, try find another one, but keep in mind that new keys won't drop as long as you still have one in your inventory ( @[GM]-Ruin this might be a bug, I don't know). If it's the correct key go back to the statue and click it. The third room is practically the same as the first one so I don't have to explain. When all mobs are killed you return to statue again and open the 4th room.
In the 4th room, you have to kill a mini-boss named "Ignator". He spawns always on the same place somewhere left in the beginning. Once you killed it go back and open the fifth room. In this room, you need to open all the seals with "maat stones", these drop from the mobs that spawn there. But you will always have to open the first one correctly before you can open them all, so you'll need some luck there. Here aswell, maats won't drop if you still have one or more in your inventory. If all seals are opened you can openen the last room, where you just have to kill a metin stone. Once you did this, you click the statue a final time, and you will all be teleported/spawn in the Razador room.
When you entered the Razador room, it's better to take the Razador together with some mobs to a wall and kill those mobs first. Once this is done, you all wait for 5-10 seconds, before you attack to let the Razador "unbug". (It happens, that Razador can't be attacked due to a "bug", if this happens you have to let the Razador do a skill/attack, and then you will be able to attack him.)
If Razador is dead, he will drop whelp boxes, pet book box, transform or enchant costume and ward/boost book chests. The ward/boost book chests aren't that good, but if you need them for your ward/boost skill, it's good to pick up some of them. After you killed him and picked up your drops, all players will be teleported back to the entrance.
The cooldown on Razador is 30 minutes for group dungeon (don't know it for solo 
)
So now I will just summarize the whole run in a few steps.
Room 1 : Kill all mobs
Room 2 : Kill mobs > drop golden cog wheel > open seal
Room 3 : Kill all mobs
Room 4 : Kill Ignator
Room 5 : Kill mobs > drop maat stones > open seals
Room 6 : Kill the metin
Razador : Kill Razador > enjoy drops
Greetings
Hephaestos ;-)