Down below,
you’ll find a spreadsheet with every item in the game with all sources of resistance reduction, all three resistance reductions are covered [Type A = -X% resistance ; Type B = X% resistance / Y second(s) ; Type C = X resistance / Y second(s)]. The file was created by Libre Office Calc, no deep functions were used so the file should work in every office application, which can read / modify ODS files.
The file is provided through Google Drive:
Online version in XLSX format, stored on Google Drive. This version includes GD, AoM, FG, SEASON 4 ITEMS and SEASON 5 ITEMS! The file is open for being downloaded and commented. The file is being updated when any new patch is released or if a mistake is found or being reported.