There are a number of concerns with her still, particularly her getting stuck on the board after tapping. As she is Legendary, you can't just play another. You might consider some kind of repeatable untap effect.
Ral Zarek is outside your colors, but you could probably manage
Venser, the Sojourner who effectively untaps her and is also a good way to effectively boost your life total when the opponent commits resources to attacking him.
Other things in no particular order:
Captivating Vampire synergizes with
Beguiler of Wills if you're making tons of vampires (via
Bloodline Keeper or
Sorin, Lord of Innistrad, or
Skeletal Vampire, who is bad).
Cytoplast Manipulator and
Simic Manipulator are good thieves if you can run the deck to work with +1/+1 counters (proliferate would work with the Planeswalkers mentioned too).
A lot of those things also interact with Rings and Elixir like you wanted; Planeswalkers are really good to ability-copy, as are the token generators.
Just some thoughts. Good luck with the deck.