We can glean a bit from the source code to EQ EMU. Here's the spells code(in C++);
https://github.com/EQEmu/Server/blob...one/spells.cpp
Now, it's critical to note that Project 1999 is a custom fork that endeavors to mimic a much earlier version of the game so potentially that file is far different here. The devs do not (and are not required to) make that source available.
Assuming that it is close, then these comments from the function
isCharismaCheck() (line 4637) are very helpful:
Code:
/*
Charisma ONLY effects the initial resist check when charm is cast with 10 CHA = -1 Resist mod up to 255 CHA (min ~ 75 cha)
Charisma less than ~ 75 gives a postive modifier to resist checks at approximate ratio of -10 CHA = +6 Resist.
Mez spells do same initial resist check as a above.
Lull spells only check charisma if inital cast is resisted to see if mob will aggro, same modifier/cap as above.
Charisma DOES NOT extend charm durations.
Fear resist chance is given a -20 resist modifier if CHA is < 100, from 100-255 it progressively reduces the negative mod to 0.
Fears verse undead DO NOT apply a charisma modifer. (Note: unknown Base1 values defined in undead fears do not effect duration).
*/
And just below that;
Code:
//Lull spells DO NOT use regular resists on initial cast, instead they use a flat +15 modifier. Live parses confirm this.
//Regular resists are used when checking if mob will aggro off of a lull resist.
Personally, I play my enchanter as a 'charisma over everything' junkie and I can feel when adorning grace wears off and I drop from 255 to 216 charisma.