That's a very valid point, I've only ever built Rylai's as a late game HP item since I didn't go for a much earlier Rod of Ages in most cases. Her Q and R have the duration matched by their stuns/slows, and I'm not sure if Zenith Blade counts as an AoE spell for the reduced effectiveness. At best it'll enhance the slow if you miss the stun zone on her R.

I only build Rylai's to enhance Zenith blade for the sake of getting ahead of enemies to hit them with Shield of Daybreak, since it's pointless to Zenith in with a SoD charge - but Rod of Ages is overall a better pick, but Frozen Mallet could be a better substitute even on AP builds, it sacrifices less than 40~ damage for more bulk if your team needs the slowing item.

I'll update the cheat sheet after the Ziggs patch, the input is much appreciated.

Rylai's Crystal Scepter is a bit useless on leona, considering you E, immobilise then stun, your R should usually stun. your W, well if you have cdr you will have a Q or E up anyway soon so don't need the slow.

Rylai's effectively only works on W.

Loving the bruiser Leona, a ton of fun to play

Really good looking Leona guide, looks like you put lots of effort into it :) +1