What makes you exclude passive abilities? For example, it would make sense if ominous mist prevented 
production by luminescent creatures, although I'm not so sure about the others.
That's a fair question. I had a few reasons both practical and conceptual:
1/ This card is modeled after Sundial. With Sundial, you prevent creature attacks but do not prevent spell damage, weapon damage or creatures from using their abilities. In the same way, I wanted to keep this card limited so as not to get into the "OP vs not-OP" debate.
2/ I wanted to keep the cost low. If it denied all abilities both active and passive, I think the cost would have to rise.
3/ I figured being scared by the mist would prevent creatures from taking action (active abilities) but not from being who they are (passive abilities.)
4/ Since devourers/pests are a staple of
decks, preventing the passive ability would nerf them as much as any creature and thus relegate this card to non-usability.
It would be an interesting addition if this card had special affect on
producing creatures since Holy Light has unique effect on
/
creatures. How would you word the additional ability for the card?
