Lord of light events are a cornerstone of the game, and one of my favorite events. They are short lived though (3 or 4 days at most).
During those, LOL levels will have an increased chance to drop rare souls, so that’s already good.
You will also collect event toon fragments (usually different toon than the dungeon event) so once again, chance for a brand new toon and sacrifice worthy dupes.
Finally, these events also drop lillith fragments. Lillith fragments are great because they give out lillith souls, and each lillith soul opened means 100 frontier coins. And that’s not counting the 5* lillith itself. This is a great value in a single soul. If you don't have your arsenal of Lilith characters complete, it's great. If you already have them all, then they're great sacrifice material.
So once again a few words of advice :
Level VII gives almost the same rewards as level X, so if you don’t have the adequate team to farm level X, go for VII
Don’t hesitate to spend ironite on those, remember : event toons + lilliths + rare souls = great value
LoL also give out a lot of resources to level your toons, be it to use them or sacrifice them
LoL events usually take place a few days before the start of the sacrifice event, so this is your chance to get sacrifice ready toons