Mörk Borg you roll to cast. You get a random number of invitations a day. But if you fail the roll you take damage and can’t cast that spell for a while, plus a crit fail can earn you a roll in the crit fail table.
I think I like Shadowdarks the most, but I might add mercurial magic from DCC.
One thing I thought of recently when everyone lost the ability to sleep in one of our Miörk Borg campaigns was to provide a ritual to get back a spell.
Which led me to consider that for Shadowdark and DCC.
If you fail a spell you can’t cast it again unless you commit some ritual. That would remove the “daily” recharge thing.
The rituals would be a little risky and cost something. Maybe riches, those expensive components that usually get ignored, or maybe they’d have to “spellburn” or roll for crit failure every cast. Not sure yet.