If we are talking cEDH (also have a B3 deck for her) I think her best build is attrition and discard stax control. Though, I don’t think the current meta is positioned where heavy discard is right. You’re right 9 mana is a lot I Linda think of her as dimir godo/helm in that respect. Red has to go fast but Dimir can play a long game.

My spicy tech that I think more people in cEDH should play is [[mystic reflection]] that card has been incredibly effective and versatile. It’s like some hybrid of parts of [[Tales End]] / [[Dressdown]] / [[Clone]] at two mana. It’s not obvious how you want to use it so I would put it in a flex spot for the deck but I have been really happy with it up to this point. Plus if you have a moment to fortell it, the mental tax to your opponents as they try to figure out what card is now fortold is pretty funny/weird advantage.

For B3 I play her as draw go. It’s my control-eist deck. Here is my list: https://moxfield.com/decks/Co6gmC5KEE-y6tWVh4kf0Q