When you throw a Lux E (Lucent Singularity) under an enemy while having Rylais Crystal Scepter – how does the slow passive (from Rylais) proc with the spell? Does it add it's slow to the Lucent Singularity (which already slows the enemy champion) or does it proc after the spell was activated?
How about her passive? Does popping her passive with an auto attack proc rylais?
Best Answer
Lux's E does not do damage until it is activated again or times out, Rylai's procs only on magic damage, so the slow from Lux's E can't proc Rylai's passive.
Slows in LoL other than just item slows can stack, so any slow applied after a target was already slowed increases the slow amount. In patch 0.9.22.15 "Removed the internal 6 second cooldown." for Rylai's passive. So I'm guessing the damage from Lux's passive and the damage from Lux's E can both apply Rylai's passive, but since item slows don't stack it will only refresh the slow, not increase it.
Also note that Lux's passive is single target and will therefore apply Rylai's 35% slow, while the damage from Lux's E is aoe and only applies the 15% slow. Any item slow on a champion already affected by an item slow will only apply if it is a stronger slow than the previous slow. Keep in mind that proccing the passive after activating Lux's E will increase the slow as well as refresh it.
References:
Lux E description from lol wiki:
Rylai's passive from lol wiki:
Notes on item slow, in Rylai's lol wiki page: