Classes

Assassin

The Assassin Prince's quest is available to Assassins as early as level 30 (other classes must be level 45).

Bard

Level 25 ability grants knowledge in 6 skills that aren't maxed - this can be ANY skill, and does not have the restrictions imposed on character creation. They gain Rnd(20) + 20 in those skills.

Thief

Lvl32+ Thieves Cannot steal items with value <= 10 

Thieves-6, appear to get a bonus to finding secret doors (and the quickling tree?)

Elementalist

((This needs to be made into a table.)) Level Spell Increase MaxIncr 1-4 Burning Hands Level * 5 + 50 5-14 Burning Hands Level * 4 + 35 15+ Burning Hands Level * 3 + 25 1-4 Frost Bolt Level * 2 + 15 5+ Frost Bolt Level * 4 + 50 5-14 Fire Bolt Level * 5 + 15 15+ Fire Bolt Level * 5 + 25 5+ Fireball Level / 3 10 10+ Earthquake Level / 2 5 15+ Imp. Fireball Level / 4 5 20+ Lightning Ball Level / 4 5 25+ Ice Ball Level / 4 5

Farmer

Level 32 ability: Trains Str by (Level*5)-155)*4, Dex by (Level*5)-155), and Tou by ((Level*3)-93)*10

Paladin

The Holy Avenger artifact sword does double damage for paladins. 

Merchant

At level 25, immune to ambushes. 

Monk

Monks don't receive the negative effects of writing difficult scrolls that other classes do.

DV Bonus = (Level * 2) / 3 If Not Wearing Body Armor except specific ones.

Monk-Safe Armor: Robe, Black Robe, Shirt of the Saints, Robes of Resistance, Elven Chain Mail, Clean Robe, Clothes.
ALSO, you cannot be weilding a shield for this bonus to apply. 

Gets + Level/2 bonus speed.

Beastfighter

DV Bonus is Level / 3 

Gets a bonus when fighting animals. Gets + Level/2 bonus speed.

Mindcrafter

Mental Shield DV Bonus = (Willpower + Level) / 5

Mental Shield PV Bonus = Willpower+Level / 8 

Necromancer

Can create increasingly better slaves at higher levels:

Level

Creature

Mana Cost

Lvl. 40+ Mana Cost

1

Zombie

1

1

6*

Skeleton

1

1

6

Ghul

1

1

10

Shadow

2

1

13

Corpse Fiend

2

1

16

Wight

2

1

19

Wraith

2

1

25

Mummy

3

1

29

Skeletal Warrior

3

1

33

Ghost

3

1

37

Spectre

4

2

41

Vampire

X

4

46

Shadow Lord

X

5

50

Lich

X

8

You can get skeletons before level 6 (at least by level 5) randomly instead of zombies. However, the menu where you can actually chose is only available at level 6.

Good repeatable sources for more powerful corpses are the Quickling Tree, Minotaur Mazes, and Stone Giants from Mining.

Shadow Touch (level 25 ability) will regain HP first; if maxed, it will regain PP instead. PP Gained is damage Dealt / 2? HP Gained is damage Dealt / 3? If 1d10000-1 < Damage Dealt?, you gain 1 mana. Can lower alignment, possibly depending on monster's alignment?

Merchant

After a normal PC has taken 5000 turns, the prices in all shops (except Terinyo) go up. They don't go up if you're a Merchant. (Note - not completely verified; requires further testing.)
Merchants can use gold as a missile weapon effectively. This als means they can hit Doppelgangers with a missile weapon, which other classes cannot.

Ranger

Level 12+ takes only 1/3 of drowning damage? 

Weaponsmith

Level 6 melting ability is determined by the weight of what you're melting down as far as how many ingots you'll get. This means for example ultra-heavy armors are especially nice for melting down.
Unucursed Hammer & Uncursed Metal = 72:10000; Blessed Hammer & Uncursed Metal = 81:10000; Cursed Hammer & Uncursed Metal = 56:10000; Cursed + Cursed = 44:10000; Uncursed + Cursed = 56:10000; Blessed + Cursed = 63:10000; Blessed + Blessed = 90:10000; Uncursed + Blessed = 81:10000; Cursed + Blessed = 63:10000.
Failing a Smithing roll halves the amount you get. 

How Good their crowning gifts are: Weaponsmith: 3 Great (BoW, Protector, RoI), 1 Good (Skullcr), 1 Decent (Hammer), 1 Poor (Perion) = 5.8 Beastfighter: 2 Great (Bow, Preserver), 4 Good (Oman, 2xCompan, Divine)= 5.8 Mindcrafter: 1 Great (RoI), 4 Good (2x RoR, Brannal, Havlor), 1 Average (Wanderer) = 5.3 Necromancer: 2 Great (RoI, Preserver), 2 Good (RoR, Kinslay), 2 Decent (Vanquish, Archmagi) = 5.3 Paladin: 2 Great (2x Justifer), 2 Good (Trusted, Scarf), 2 Decent (Perion, Hammer) = 5.2 Priest: 4 Good (Scarf, Shirt, Skullcrush, Purify), 1 Decent (Hammer), 1 Poor (Justify) = 4.8 Healer: 1 Great (Preserver), 3 Good (Brannal, RoR, Shirt), 2 Average (Shez, Wanderer) = 4.7 Monk: 2 Great (RoI, Shirt), 3 Good (RoR, Havlor, Divine), 1 Average (Shez) = 4.7 Assassin: 4 Good (Execute, Farslay, Kinslay, Oman), 1 Decent (Serpent's), 1 Poor (Death's) = 4.2 Wizard: 1 Great (RoI), 2 Good (Brannal, RoR), 2 Decent (2x Archmagi), 1 Average (Wanderer) = 3.6 Elementalist: 1 Great (RoI), 2 Good (Havlor, Brannal), 1 Decent (Archmagi), 2 Average (Wanderer, Nature's) = 3.5 Fighter: 2 Great (BoW, Protect), 1 Good (Vanquish), 1 Decent (Grod), 2 Average (LSting, Death's) = 3.4 Barbarian: 4 Good (2x Vanquish, 2x Skullcrush), 1 Decent (Grod), 1 Average (Death's) = 3.0 Merchant: 3 Good (Trusted, Havalor, Leader), 3 Average (Shez, Wanderer, Divine) = 2.9 Farmer: 2 Good, 1 Decent, 2 Average, 1 Poor = 1.5 Ranger: 2 Good, 1 Decent, 2 Average, 1 Awful = 0.8 Bard: 2 Good, 2 Average, 2 Poor = 0.6 Druid: 2 Good, 2 Average, 2 Poor = 0.6 Archer: 2 Good, 1 Average, 1 Poor, 2 Awful = -1.1 Thief: 1 Good, 3 Poor, 2 Awful = -2.9

Valuations: 4.5, 3.0, 1.6, 0.8, 0.3, 0 Dwarves (Except Monks, Beastfighters): +Good (1) * 6/7 High/Gray Elves (Except Beastfighters): +Good (1) * 6/7