Like the Berserkers Clash Limit Quests, these quests lack a stamina cost, but a higher than usual skill ceiling. There's two phases per battle, and while there's no drops at all, the quest rewards you with an abundance of God Crystals in place of a Transient Stone like typical first-time quest completions.
It is highly advisable to shy away from using Blow users and focus on using units with wider spread or higher penetration, as all the Genin units have either Shot or Magic (they're all Magic on the level 60 one, but some Genin may spawn as such).
You can also abuse AI priorities and behavior to prevent getting overwhelmed.
Each quest contains battles with a board size of 5x6, and two phases instead of four, and replaced the Transient Stone rewarded on completion with other items.
The first quest rewards you with +10 NETHERGod Crystals. Genin attribute and whether they're Magic or Ranged are random.
On the main map, an area called "Past-Events" will appear, offering quests of events passed for no-stamina cost, but without the rewards. This is mainly for players who originally missed out on these event quests, as pre/post-quest story can always be viewed under Recorded Memories. Naturally, current-running events can't be accessed from the Past-Events area. However, any future events may impose a cost (Transient Stone or Coins)