Lowest level challenge

[impy]

hotfix666: student belt = +1def, +1int,plus 8% probability of getting a dominant rune of character class per fight. As you can see, it is open to abuse, just replay every battle...

Right, the only compulsory fights & quests in order to finish the game are as follows:
Montero guardian - 1055exp
Gremlion - 16000
Demenion - 13016
Ktahu - 20000
Rakush - 7765
Uchkuk - 10455
Shenobi - 15191
Open mirror tower quest - 4590
Spirit of sorrow - 4585
Stone inside Tekron - 1762
Amulet of Illumination - 153
Hagni - 5987
Temple of love quest (hagni) - 1700
Baal - 26000
Reha warriors - 14155 + 18353
Reha warriors quest - 7650
Total: 168417exp = level 30

Also, if you play with droids, there is immensely helpful Axe of Ice (10% phys.res, no retaliation for repair droids, +7defense) which is additional 3740 exp. ; for a total of 172157exp.
Just to have it complete, here is a list of level requirements
Level 30 - 158100exp.
Level 31 - 175100exp.
Level 32 - 193800exp.
Level 33 - 212500exp.
I don't think it is humanly possible to finish the game at level 30. Playing with droids you have cca 2900exp to spare, with black knights it is 2900+3740=6640exp to spare. But this extra experience has to cover experience gained from all early fights (to work on medals) + experience from fighs for new continent scrolls (if you cannot kite them all) + experience from non-compulsory castle battles containing all important artefacts you want. Therefore level 31 seems more realistic, giving you 2900+17000=19900exp to spare with droids and 6640+17000=23640exp to spare with black knights.
I finished the game with cca 215000exp. This is where extra experience come from:
-fight for elon scroll in verona = 2235exp
-antidote quest in order to get twinkling boots = 4500exp
-fight with octopus in scarlet to get to dwarf (slippery cuirass) = cca 1000exp
-scarlet, dwarf's quest, getting 9 runes = 2500exp (bad decision)
-montero, quest levers & gears in order to get access to royal hammer - 1870 exp
-killing professor dambior for +25%magic res. regalia = 7500exp.
-fighting Baal with Learning 1 - 10% extra exp = 2600exp.
-fighting Gremlion with Learning 1 - 10% extra exp. = 1600exp.
- Umkas, fighting for Uzala scroll - ??4000exp???
that is total of cca 27000exp. The remaining 215000exp - 27000exp - 172157exp = 16000exp must have come from early fights when working on medals.
I made a big mistake not making sure that magician cowl and/or mirror shield appear in my game. I thought that chaos crown + crystall ball +leather dress + guardian 3 medal = 17% magic resistance for droids would be enough for defeating Gremlion. Maybe so, this was my first playthrough with droids in my "career" so i gave up eventually, killed Dambior and went for neatness 3. That forces you to take Learning 1. So 2600exp+1600exp+7500exp = 11700exp could have been saved.

What is an ideal setup in my opinion?
Hero : Twinkling boots, Scaly set, Royal hammer, Horn of king borg, crown of chaos, Engineer's badge
"business associate" Agvares - Axe of Ice, Slippery cuirass, Belt of the winner, unupgraded painskull for hero fights, crystall ball/portrait of ice queen for boss fights
Slippery cuirass can be swapped for leather dress or magician cloak if other resistances are needed. Of course, i did not have all of it