As of today (April 13th), this is the best-performing Lady in White deck reported at hsreplay.net, with a 59.3% winrate over 460 games in the Legend to Rank 10 bracket.
I searched for it on Hearthpwn, saw that it wasn't posted here yet, so here it is for discussion.
If there's interest, I will modify this deck over time to reflect whatever's the best-performing Lady/Keleseth deck in Legend to Rank 10 going forward.
I'm not actually playing this deck (yet), though I plan to. If someone else wants to post the same deck at Hearthpwn with a guide I wouldn't mind at all.