While covert magic uses secrecy or the cloak of happenstance to hide its true nature, ordinary suspension of disbelief only stretches so far before it snaps and turns into incredulity and disbelief. Basically, the more often mages perform covert magic in a particular place and time, especially the same covert magic, the more likely their magic crosses the line and risks a Paradox. Covert spells can become improbable. Some mages call this the “domino effect,” since it’s like tipping over a line of dominoes.
For example, it’s not hard to believe lightning might strike someone from a cloudy sky, particularly if there’s a storm brewing and the target is standing out in the open. Lightning striking the same target twice, however, is much harder to believe, and lightning striking multiple targets multiple times in the same area over a short period is almost impossible to dismiss as coincidence. One lightning strike is coincidental. A dozen is highly improbable. (See the Forces “Call Lightning” spell.)
There’s a fine line between the two, and ultimately it’s up to the Storyteller to decide when a mage is about to cross it. Generally, if the reaction of Sleeper witnesses is likely to be “Wow, what are the odds?” then there’s no chance of a Paradox. If it’s more likely to be “No way, that’s impossible!” then the spell risks a Paradox. Mages know when the jig is up. They can sense when coincidence is stretched too far to be pushed any further, so the Storyteller should always warn players when their characters are about to step over the line, telling them before they roll the dice something like, “That spell will exceed the threshold of credibility and risks a Paradox.”
