Note: this mod requires EEEx

This mod allows casting level bonuses from various sources to accumulate. By default, CL bonuses in the IE games do not stack -- the last-applied effect always wins. This changes their underlying behavior to enable accumulating these bonuses from all sources (items, spells, proficiencies, class abilities, creature effects). 

This also works with on-the-fly changes like Wild Mage casting level changes or temporary buffs like the Kappelmeister Bardsong from Bardic Wonders mod.

Install very late, like absolute-last-mod-late. See GitHub for more instructions.

Download: GitHub

Discussion: G3, Beamdog