Congrats! My ally got her too today, I pulled Marie Thérèse instead this thursday.
I think Locke is good. There are not that many 5* dispellers (though Viv can be gotten from TC20) and unless you’re able to charge yours and have him/her ready when Locke fires, you may be screwed, as that poison of hers takes more than 50% of most heroes’ HP. Combine that with some regular hits and it is a problem. She is completely screwed by Grazul though.
Btw only today I noticed she is in fact undead. Creepy. Maybe MT animated her?