I finally found info on how spell penetration works, and made a simple "infographic" on Desmos! https://www.desmos.com/calculator/bqaac6rtnq : r/elderscrollsonline
ESO Alchemy Essentials: Essence of Spell Power Potion - BenevolentBowd.ca
Skill Calculator - ESO-Skillfactory
Skill Calculator - ESO-Skillfactory
Understanding ESO Damage Scaling - Hack The Minotaur