Board Thread:Episode Discussion/@comment-24993958-20171021151743/@comment-4010415-20171024023831

The Boarbatusk didn't exactly push her to her limits, though.

Winter's wording was "Now think to your fallen foes! The ones who forced you to push past where you were, and become who you are now."

It kinda makes it sound like the enemy that they defeat has to have some kind of lasting impression on them through the fight causing them to change in some way.