Every step you must take to progress, in order, with the optional things worth doing along the way. Tick steps off as you go; your progress is kept in this browser.
Spent in the Spellbook and on two rituals. Sources: studying at the Research Table (+2), the Ritual of Insight (+3), Torn Spellbook Pages from wizard towers (+3), Rogue Apprentice notes (+1), Lost Pages (+5) and the Research Engine.
You start with 100. Each Ritual of Deepening adds 25 (up to 300), Ascension adds 50, the first Colossus kill adds 100 and becoming Archmage adds 100.
Forbidden spells add it and it fades about one point a minute. Whispers at 25, darkness at 50, withering and hunger at 75. Holy Water, the Ritual of Cleansing, the Wisp familiar and the Arcanist's Garb all help.