Board Thread:The Quarters - Q & A/@comment-2606:A000:47C9:9000:F9DD:F112:CED3:46CB-20171026032848/@comment-25085701-20171026181255

Ah, well the skills/spells themselves are the incentive in most cases.

Attack spells (like Burst of Flames and Brutal Smash) damage boss monsters during quests.

Buff spells (like Tools of the Trade and Earthquake) temporarily increase your stats and make your task effects more effective when you complete them.

And then there are the mana and healing spells that help the rest of your party.

The gating factor here is your mana points; you only have so many casts available and leveling up doesn't restore your mana. Completing all your tasks gives you more per-day mana regen than if you miss them, and so you can cast 'em more often. If you see it as a 'bonus XP gain bar for diligence', it falls in line with what I think you're thinking it ought to do.