He casts Silent Image to create a giant scroll a few hundred feet in the air with a mean old message written in the sky with a large font.
Can I use the message contained in Silent Image to intimidate?
Role-playing Games Stack Exchange is a question and answer site for gamemasters and players of tabletop, paper-and-pencil role-playing games. It only takes a minute to sign up.Sign up to join this community
An enormous and threatening illusion—even if it's not detected as such—can certainly be intimidating (in the real-world sense of the word), but that enormous illusion won't, for example, allow the illusion's controller to make Intimidate skill checks against the populace.
The Intimidate skill's most common uses are coerce opponent, which affects a lone target and takes a long time; demoralize an opponent, which only works against a lone target within 30 ft. of you; and influence an opponent's attitude, which only works against a lone target.
Against a lone foe, this GM supposes that part of the coercion skill use could be conducted via the written word sent to the target directly or projected overhead if the bully is also a ham and that the demoralize opponent skill use is probably possible through projected words alone although that seems a shameful waste of a spell, but this GM would rule that the influence an opponent's attitude skill use can't be employed via a static illusion as that skill use specifically mandates conversation.
This doesn't mean that the GM should ignore the effects of the illusion, though! If the caster skywrites for the land to see The king's a demon! or The princess is a traitor! then the caster likely has the populace's attention even if the populace isn't coerced, demoralized, or influenced!