Kai'sa and Luden's Echo

I was curious to know how Kai'sa interacts with this augment and I'm just documenting it here if anyone else wants to know.

I just made the experiment and here is how it works:

Luden's will proc in the first stack pop AFTER she casts her buff. Only one time per cast. Will not proc before the first cast.

If you know a champ that also uses Ludens's in a kinda strange way, please comment below :)