Either a perfect parry or perfect soak, IIRC; maybe have it fail after an attack that has some amount of raw damage. If stuff can continue on to hit her after breaking the shield, high hardness (and soak) that's gone for [insert very short timeframe] after it's beaten would also work
Well, how do you overcome it in Worm? You hit it hard enough to bring it down, then hit her again right thereafter.
Mechanically, that's probably best realized as a perfect parry with a weakness to multi-attack charms or simultaneous attacks, including a requirement that the attacks do at least this much damage.
In 3E, I'd probably model it like this:
Her Force Field has a Magnitude just like a Battle Group. As such, you can weaken it with both decisive and withering attacks, though decisive attacks do more damage.
If you want to be more generous, it's not actually Magnitude and just something that works similar, but gives you Initiative when you hit it. That'd make sure enemies can build momentum against her.
It can't take any actions, but uses a perfect defend-other on Glory Girl at all times. Thus, it's actually really hard to wither down her Initiative as well as to injure her.
The Force Field recovers it's magnitude in regular intervals - either after each tick, or if you want to be more generous each time Glory Girl acts.
Then we give her some charms that work off this force field - notably, she can expend it for one tick to boost an attack of hers, but that exposes her to a clash-attack.
Of course, this would be a really rather powerful effect. Virtually unbeatable against a single opponent who doesn't have multi-attack charms, and still really strong in every other circumstance. But such is the nature of (some) Worm superpowers. If you put an effect like that on a non-Exalt, it can actually be a reasonably interesting challenge.
