League-of-legends – Does Rek’Sai’s Q have on hit proc

From what I have done and seen, and from what I have read, it does indeed proc multple times when striking multiple enemies with AoE attacks that proc on-hit effects. So Shyvana's Twin Bite in her dragon form would instantly proc twice if you strike four targets with it, four times if you manage to hit eight. Same with Spray and Pray.

(P.S. The chain lightning effect also appears to cause spellvamp.)

I'm thinking it does add the slow from Rylai's. I've been looking on the wiki's and I found this:

The following will not trigger a slow:

• Champion abilities that do not trigger spell vamp
• On-hit damage damage dealt by items
• Summoner Spells, such as Ignite and Smite.
• Damage dealt by the auto-attacks of Clones and Pets/Minions.

http://leagueoflegends.wikia.com/wiki/Rylai's_Crystal_Scepter

Then on this page http://leagueoflegends.wikia.com/wiki/On-hit_effect#Items I found under:

Abilities — do apply spell vamp:

Area Of Effect
The following effects deal area of effect damage, but are not classified as splash damage: Cho'Gath's Vorpal Spikes