This is how I would do that:
1. extract prc_include.hak to c:\prc_include
2. edit prc_inc_castlvl.nss like this:
+ (GetLevelByClass(CLASS_TYPE_BLADESINGER, oCaster) + 1) / 2
+ (GetLevelByClass(CLASS_TYPE_BONDED_SUMMONNER, oCaster) + 1) / 2
+ GetLevelByClass(CLASS_TYPE_PALEMASTER, oCaster)
+ (GetLevelByClass(CLASS_TYPE_HATHRAN, oCaster) + 1) / 2
+ (GetLevelByClass(CLASS_TYPE_HAVOC_MAGE, oCaster) + 1) / 2
+ (GetLevelByClass(CLASS_TYPE_SPELLSWORD, oCaster) + 1) / 2
+ (GetLevelByClass(CLASS_TYPE_THRALL_OF_GRAZZT_A, oCaster) + 1) / 2
3. extract prc_spells.hak to c:\prc_spells
4. copy nwnnsscomp.exe to c:\prc_spells
5. start windows command line and change dir to c:\prc_spells
cd c:\prc_spells
6. compile all scripts with this command:
nwnnsscomp.exe -o -g -i c:\prc_include *.*
7. use compiled scripts to create new prc_spells.hak (overwrite the old one)
8. edit classes.2da and in ArcSpellLvlMod column for pale master put 1 instead of 2.
9. add edited classes.2da to prc_2das.hak
That's all
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