Jack and the Flame Guardian

When Weasel summons Yggdrasil, Jack tries to draw strength from his wish to avenge his father's defeat and surpass his father to defeat Vizel. Soon after Jack regains his advantage, Weasel summons a powerful Guardian, Bird of Rotten Wood that destroys trees, easily defeating almost all of Jack's abilities. Jack, in a final attack, summons his second Guardian and defeats both Yggdrasil and Bird of Rotten Wood, besting Weasel and surpassing his father.