You’ll encounter Mythal as a character toward the end of the Regrets of the Dread Wolf quest line in Dragon Age: The Veilguard. She is an elven mage found

No RPG is complete without a dialogue pop quiz and you're going to get a deadly one when you try to obtain Mythal's essence in Dragon Age: The Veilguard. If you collect all the wolf statuettes to complete the Regrets of the Dread Wolf quest,

The Veilguard and uncovered all the pieces of Solas’ backstory, a new quest will unlock that gives you a brand new power. Go to the Crossroads and you’ll find Morrigan who explains that you’re about to encounter a vestige of Mythal,