Further Upgrades The first cards I'd pick up to further juice up the deck would be untapped mana-fixing lands: Watery Grave, Shipwreck Marsh, Underground River, Morphic Pool, Darkslick Shores, Polluted Delta, Sunken Ruins, Undercity Sewers, Urborg, Tomb of Yawgmoth and then maybe a couple more Island / Swamp fetches
If youre building towards affinity, you need to draw a bunch of artifacts
Any of the more expensive colorless instants like Scour from Existence can get you a pretty big card off its cascade trigger while still being a good card in and of itself
This makes her a little tricky to remove, both because it requires opponents to invest more mana into getting her off the battlefield and because it forces them to spend their own life to do so