We're all pretty familiar with the Haw-thorns build by now, I believe.
Lord Hawthorne
-Might of Daqan
-Shield of Margath.
Lord Hawthorn has a defense of 3, but Might of Daqan boosts that to 4. He also has a white defense modifier, allowing him to get up to 5 defense. Shield of Margath says, "After defending against a melee attack, the attacker suffers damage equal to your defense. Now, this works decently on Hawthorn because 5 defense is a big deal, so he's not taking as much damage while also hitting enemies back.
Well, I was looking at Kethra and wondering if she might not be another decent recipient of the Shield of Margath. Kethra has some early-initiative options to pair with her blue +1 defense modifier, such as an initiative-2 speed-1 march or an initiative-3 rally. This boosts her to defense 4. With Shield of Margath, she'd dealing 4 damage to an enemy making a melee attack against her. But wait, there's more! She can choose to give herself the Unnatural Growths condition during setup. If I'm reading it right, it deals 2 damage to an enemy making a melee attack against her. With Shield of Margath, she could be doing 6 damage in retaliation, beating Lord Hawthorne in terms of damage!
It's a fun idea, but I think it probably won't work for 2 reasons. First, she doesn't have as high a defense as Hawthorne. You're basically trading 1 point of defense for an extra point of damage. I'm not sure she would last long taking damage like that. Second, you're forfeiting a lot of her utility by having her activate early and buff her defense. With 2 white dice and her neat skill ability, you probably want to be doing more with her than just rallying. At 6 points, you can probably find better options for Kethra A'laak than Shield of Margath. Still, it looks like she wins the static damage competition!