Last revised 5/26/24 .
Basic/Expert D&D is known for, among other things, its low level limit compared to other editions. I wanted to allow characters to level beyond these limits, so I used the optional rules listed in the Old-School Essentials book to expand all the Advanced Fantasy classes (and race-classes) into high levels. I don’t know if anyone will ever reach these levels, but I like having the option available.
I have attempted to expand each class into higher levels without dramatically increasing the power level of the game too much or adding additional mechanics. The only thing new from a B/X standpoint is the addition of extra attacks for some classes. After a certain threshold, every class only advances in hit points.
Acrobat
Level XP HD THAC0 Tumbling Attack 15 880,000 9d4+12* 12 [+7] x3 16 1,000,000 9d4+14* 12 [+7] x3 17 1,120,000 9d4+16* 10 [+9] x3 18 1,240,000 9d4+18* 10 [+9] x3 19 1,360,000 9d4+20* 10 [+9] x3 20 1,480,000 9d4+22* 10 [+9] x3 21+ +120,000 +2* 10 [+9] x4
* Modifiers from CON no longer apply Assassin
Level XP HD THAC0 15 1,050,000 9d4+12* 12 [+7] 16 1,200,000 9d4+14* 12 [+7] 17+ +150,000 +2* 10 [+9]
* Modifiers from CON no longer apply Barbarian
Level XP HD THAC0 Attacks per Round 15+ +130,000 +3* 10 [+9] 2
* Modifiers from CON no longer apply Bard
Level XP HD THAC0 1 2 3 4 15 960,000 9d6+12* 12 [+7] 4 4 4 3 16 1,080,000 9d6+14* 12 [+7] 5 4 4 4 17 1,200,000 9d6+16* 10 [+9] 5 5 4 4 18 1,320,000 9d6+18* 10 [+9] 5 5 5 4 19 1,440,000 9d6+20* 10 [+9] 6 5 5 5 20 1,560,000 9d6+22* 10 [+9] 6 6 5 5 21 1,680,000 9d6+24* 10 [+9] 6 6 6 5 22+ +120,000 +2* 10 [+9] 6 6 6 6
* Modifiers from CON no longer apply Cleric
Level XP HD THAC0 1 2 3 4 5 15 800,000 9d6+6* 12 [+7] 6 6 5 5 4 16 900,000 9d6+7* 12 [+7] 6 6 6 5 5 17 1,000,000 9d6+8* 10 [+9] 6 6 6 6 5 18+ +100,000 +1* 10 [+9] 6 6 6 6 6
* Modifiers from CON no longer apply Druid
Level XP HD THAC0 1 2 3 4 5 15 1,650,000 9d6+6* 12 [+7] 6 6 6 5 5 16 1,800,000 9d6+7* 12 [+7] 6 6 6 6 5 17+ +150,000 +1* 10 [+9] 6 6 6 6 6
* Modifiers from CON no longer apply Dwarf
Level XP HD THAC0 Attacks per Round 13 1,300,000 9d8+12* 10 [+9] 1 14 1,600,000 9d8+15* 10 [+9] 1 15+ +300,000 +3* 10 [+9] 2
* Modifiers from CON no longer apply Elf
Level XP HD THAC0 1 2 3 4 5 Attacks per Round 11 1,200,000 9d6+4* 12 [+7] 4 3 3 3 2 1 12 1,500,000 9d6+6* 12 [+7] 4 4 3 3 3 1 13 1,800,000 9d6+8* 10 [+9] 4 4 4 3 3 1 14 2,100,000 9d6+10* 10 [+9] 4 4 4 4 3 1 15 2,400,000 9d6+12* 10 [+9] 5 4 4 4 4 2 16 2,700,000 9d6+14* 10 [+9] 5 5 4 4 4 2 17 3,000,000 9d6+16* 10 [+9] 5 5 5 4 4 2 18 3,300,000 9d6+18* 10 [+9] 5 5 5 5 4 2 19 3,600,000 9d6+20* 10 [+9] 6 5 5 5 5 2 20 3,900,000 9d6+22* 10 [+9] 6 6 5 5 5 2 21 4,200,000 9d6+24* 10 [+9] 6 6 6 5 5 2 22 4,500,000 9d6+26* 10 [+9] 6 6 6 6 5 2 23+ +300,000 +2* 10 [+9] 6 6 6 6 6 2
* Modifiers from CON no longer apply Fighter
Level XP HD THAC0 Attacks per Round 15+ +120,000 +2* 10 [+9] 2
* Modifiers from CON no longer apply Halfling
Level XP HD THAC0 Attacks per Round 9 480,000 8d6+1 14 [+5] 1 10 720,000 8d6+2* 12 [+7] 1 11 960,000 8d6+3* 12 [+7] 1 12 1,200,000 8d6+4* 12 [+7] 1 13 1,440,000 8d6+5* 10 [+9] 1 14 1,680,000 8d6+6* 10 [+9] 1 15+ +240,000 +1* 10 [+9] 2
* Modifiers from CON no longer apply Illusionist
Level XP HD THAC0 1 2 3 4 5 6 15 1,200,000 9d4+6* 14 [+5] 5 4 4 4 4 4 16 1,350,000 9d4+7* 12 [+7] 5 5 4 4 4 4 17 1,500,000 9d4+8* 12 [+7] 5 5 5 4 4 4 18 1,650,000 9d4+9* 12 [+7] 5 5 5 5 4 4 19 1,800,000 9d4+10* 12 [+7] 6 5 5 5 5 4 20 1,950,000 9d4+11* 10 [+9] 6 6 5 5 5 5 21 2,100,000 9d4+12* 10 [+9] 6 6 6 5 5 5 22 2,250,000 9d4+13* 10 [+9] 6 6 6 6 5 5 23 2,400,000 9d4+14* 10 [+9] 6 6 6 6 6 5 24+ +150,000 +1* 10 [+9] 6 6 6 6 6 6
* Modifiers from CON no longer apply Knight
Level XP HD THAC0 Attacks per Round 15+ +130,000 +2* 10 [+9] 2
* Modifiers from CON no longer apply Magic-User
Level XP HD THAC0 1 2 3 4 5 6 15 1,200,000 9d4+6* 14 [+5] 5 4 4 4 4 3 16 1,350,000 9d6+7* 12 [+7] 5 5 4 4 4 4 17 1,500,000 9d6+8* 12 [+7] 5 5 5 4 4 4 18 1,650,000 9d6+9* 12 [+7] 5 5 5 5 4 4 19 1,800,000 9d6+10* 12 [+7] 6 5 5 5 5 4 20 1,950,000 9d6+11* 10 [+9] 6 6 5 5 5 5 21 2,100,000 9d6+12* 10 [+9] 6 6 6 5 5 5 22 2,250,000 9d6+13* 10 [+9] 6 6 6 6 5 5 23 2,400,000 9d6+14* 10 [+9] 6 6 6 6 6 5 24+ +150,000 +1* 10 [+9] 6 6 6 6 6 6
* Modifiers from CON no longer apply Paladin
Level XP HD THAC0 1 2 3 Attacks per Round 15 1,250,000 9d8+12* 10 [+9] 3 3 2 2 16 1,400,000 9d8+14* 10 [+9] 3 3 3 2 17 1,550,000 9d8+16* 10 [+9] 4 3 3 2 18 1,700,000 9d8+18* 10 [+9] 4 4 3 2 19 1,850,000 9d8+20* 10 [+9] 4 4 4 2 20 2,000,000 9d8+22* 10 [+9] 5 4 4 2 21 2,150,000 9d8+24* 10 [+9] 5 5 4 2 22 2,300,000 9d8+26* 10 [+9] 5 5 5 2 23 2,450,000 9d8+28* 10 [+9] 6 5 5 2 24 2,600,000 9d8+30* 10 [+9] 6 6 5 2 25+ +150,000 +2* 10 [+9] 6 6 6 2
* Modifiers from CON no longer apply Ranger
Level XP HD THAC0 1 2 3 Attacks per Round 15 1,075,000 9d8+12* 10 [+9] 3 3 2 2 16 1,225,000 9d8+14* 10 [+9] 4 3 3 2 17 1,375,000 9d8+16* 10 [+9] 4 4 3 2 18 1,525,000 9d8+18* 10 [+9] 4 4 4 2 19 1,675,000 9d8+20* 10 [+9] 5 4 4 2 20 1,825,000 9d8+22* 10 [+9] 5 5 4 2 21 1,975,000 9d8+24* 10 [+9] 5 5 5 2 22 2,125,000 9d8+26* 10 [+9] 6 5 5 2 23 2,275,000 9d8+28* 10 [+9] 6 6 5 2 24+ +125,000 +2* 10 [+9] 6 6 6 2
* Modifiers from CON no longer apply Thief
Level XP HD THAC0 Backstab Multiplier 15 880,000 9d4+12* 12 [+7] x3 16 1,000,000 9d4+14* 12 [+7] x3 17 1,120,000 9d4+16* 10 [+9] x3 18 1,240,000 9d4+18* 10 [+9] x3 19 1,360,000 9d4+20* 10 [+9] x3 20 1,480,000 9d4+22* 10 [+9] x3 21+ +120,000 +2* 10 [+9] x4
* Modifiers from CON no longer apply
