The Cartographer NPC Class

This character class requires a lot of extra work by the DM. Any DM that allows PCs to hire cartographers is a really good person and probably too nice. 
          -Elminster

What's a Cartographer?

Cartographers make maps. Cartographers claim to be part of a guild but you will never be more than two in town at once. They must somehow all be connected though because if you kill one, no other cartographer will work for you. As Cartographers go up in level they tend to become mentally unstable due to all the stress of being in a dungeon.

A party can hire a cartographer to go along with them on dungeon expeditions. They cost 50 gold per level plus a 1/2 share of any treasure. They advance as thieves and save as thieves. They carry no weapons and cannot fight.

Using the Cartographer

Every turn the party spends moving in the dungeon make a mapping check for the cartographer. If the cartographer fails place a check mark on the map where the party is. At the end of the session make a map for charting the party's path. Alter the map where the Cartographer made mistakes by rolling on the screw up table and alter the players map according to the table. The Cartographer also has a passive chance to detect secret doors which is made every time the party passes a secret door. Higher level cartographers also get a passive chance to sense traps every time the party nears a trap. The cartographer doesn't know what type of trap. It's "just a feeling."

Can Players Kill the Cartographer and Take His Map?

In the dungeon cartographers right down the dimensions in a secret indecipherable code. After an expedition the cartographer returns to his home and translates his scribble into a map. This takes 1d6 days. If  a cartographer is killed in the dungeon only another cartographer could interpret their scribbles.

How Does The Mapping Check Work?  

Each cartographer has a Mapping Score that is determined by his intelligence and level. You add his Base Mapping Score and his Level Bonus to get his Mapping Score. Every time a mapping check is called for the DM rolls a d12 if the result is under the cartographer's mapping score the check has succeeded, otherwise; it has failed.

Here's the table for getting the Base Mapping Score 

Intelligence	Base Mapping Score
3	1
4-6	2
7-8	4
9-10	5
11-12	6
13-15	7
16-18	8

Here's the Table for the other Abilities. 

Rolls for secret doors and traps are made on a d6

Level	Level bonus	Find secret doors	Sense Traps
1-2	0	1	Nope
3-4	2	1-2	1
5-6	3	1-3	1-2
7-8	4	1-3	1-3

Where's The Mistake Chart?

Here it is:

roll 1d10

1. Extra doors
2. Missing Passageway
3. Left and right confused
4. Room missing
5. Room too big
6. Room rotated 90 degrees
7. Extra room
8. Passage 10 to 60 feet too short
9. Passage 10 to 60 feet too long
10. Extra secret door

 What was That you Said About Cartographers Becoming Mentally Unstable?

After every expedition the Cartographer must make a wisdom check. If the Cartographer fails the check he gains a neurosis. Here is the list of Neuroses:

1.     Alcoholism

Cartographer will try to sneak booze if no one notices and stops him he will drink until he becomes useless -1 to Mapping score for every wineskin in excess of 2 consumed.

2.    Solipsism

Cartographer no longer believes that anyone else but himself is real. He becomes reckless as by his logic he cannot die since that would cause the whole universe to cease to exist.

3.    Paranoia

Cartographer's fearful attitude gives all other hirelings a -1 to morale checks

4.    Religious Fervor

Cartographer will not shut up about god; make an extra wandering monster check every turn.

5.    PTSD

Every time there is a wandering monster or loud noise the cartographer must make a saving throw vs. turn to stone or curl up in the fetal position

6.    William S. Burroughs 

Cartographer keeps trying to shoot apples off other hirelings' heads

EXTRA:
       Cannibalism
(this replaces a neurosis the Cartographer already has from the list when rolling) Gaze long enough into some monsters and the monsters gaze into you (or something).  Cartographer will biter other hirelings if not kept closely watched. This could lead to fights or lower morale.

Conclusion

I have not had a chance to introduce this into a game yet. I am not sure if it creates too much extra work for the dm. I will probably need to make a therapist class if this is successful.