With Liandry's Torment getting a buff, I have two questions about "Spell Damage" when considering the passive on this item.
One is general: What all is considered "Spell Damage" to proc the 2%-4% burn DoT? Is there a general rule of thumb?
Second: Is Kayle's Divine Blessing [E] (empowered auto attack that also has magic damage and splash damage) considered to proc this passive because it causes "Spell Damage"?
Any help is greatly appreciated.
Thanks in advance!
For 1, any damage from a spell. Generally this means any damage from the QWER and sometimes passive of a champion. This has some weird bits things that proc on hit effects, like Ezreal's Q, don't do spell damage unless stated, and some on next attack modifiers do not count as spell damage (Nasus Q, Vayne Q). Normally if it's a spell or ability (Zed Q, Swain R) it'll apply spell effects.
For 2, Kayle's E does apply spell effects. It's in the same boat as Cho'Gath's E, where they both modify autoattacks to also have a bonus damage portion that applies spell effects.
What all is considered "Spell Damage" to proc the 2%-4% burn DoT? Is there a general rule of thumb?
General rule of thumb? Anything 
or spell vamp works on.
Other general rule of thumb? Anything that doesn't apply life-steal is considered a spell, with 1 main exception:
All on-hit effects that don't belong to 
.
On-hit effects generally don't apply on-hit effects, with those 3 exceptions.
Otherwise - Abilities that are AA rests, AA steroids, or "apply on-hit effects" will essentially apply life-steal and not spell-hit effects.
On-hit effect abilities won't apply additional on-hit effects.
And then abilities (regardless of damage type - be it physical, magical, or true) will apply spell-hit effects like Spell Vamp, Rylie's, and Torment. Some summoner spells even count towards this - Smite in particular has been used to make the plays with Olaf's spell vamp.
Second: Is Kayle's Divine Blessing [E] (empowered auto attack that also has magic damage and splash damage) considered to proc this passive because it causes "Spell Damage"?
Yup, that applies it. Kayle's one of the 3 special champions that gets an on-hit effect skill that applies other on-hit effects. For her and Cho, I'm pretty sure they're coded more where every time they attack, a swag ability is cast at the same time.
