User blog comment:FairyRaven/Fairy Tail Chapter 371: Tartarus Arc, Part 2: Song Of The Heavenly Dragon, Review and Commentary/@comment-7418318-20140215085929/@comment-7418318-20140215095300

Nope Woest, that's not what I meant at all, though I did already adress this matter in my first post with this sentence: "so it should only depend on her emotional state." I'll elaborate a bit on what I meant.

Both times Natsu went into DF it was in a combination of two factors: Ample outside supply of magic power AND a certain emotional state. Both times he was really, really pissed at his enemy and needed to protect his friends on top of it.

The battle against Chelia was just a friendly competition. She wasn't a hated enemy and nobody's life was at stake, thus she couldn't enter DF even if that air she ate contained enough power, because she wasn't in the necessary emotional state.

If Wendy saw her friends and guild mates being beaten left and right and knew that the fate of the entire continent along with millions of innocent lives rests on the outcome of this battle, it might be enough to push her into the correct emotional state.

And if the air around her by itself doesn't give enough power, maybe someone can provide a bit of air magic for her to eat.