Favorable Interventions (a d666 roll of '111' for angels, or '666' for demons) represent the Powers That Be smiling upon them, whether it's just a lucky break or the personal blessing of Lucifer. The Angelic Player's Guide (pp. 75-77) and the Infernal Player's Guide (pp. 76-77) provide descriptions and suggestions for GMing favorable Interventions; The IPG simply mirrors the APG with descriptions of favorable results for Diabolicals. Neither book describes the consequences of unfavorable Interventions. This is something I would have liked to have included in the Game Master's Guide, but I simply didn't think of it until too late. Thus, I hereby present a remedy, which I hope will be of some use to In Nomine GMs.
Just as God and Lucifer both work in mysterious ways to aid their minions, they also may take action against their foes (or maybe any random schmuck who happens to annoy them). An unfavorable Intervention means you've attracted the disfavor of Higher Powers. But this will not always be immediately obvious; neither God nor Lucifer are likely to announce their interest in every situation that catches their attention. And an unfavorable Intervention doesn't necessarily mean that anyone is out to get the character personally. Lucifer has laid "booby-trap" of ill will and nasty coincidences throughout the Symphony; you never know when some minor act might just pull the pin on a grenade Lucifer planted eons ego. The Prince of Darkness set in motion diabolical chains of events beginning shortly after the Fall, many of which have yet to reach their culmination . . . unlucky you, to roll a '666' and be standing at ground zero when the last domino in such a chain falls.
As for God . . . well, He designed the board, the pieces, and the rules. How difficult would it be for Him to know, back during the dawn of Creation, that a few thousand millennia later, there'd need to be a Malakite walking by a particular streetcorner just as some poor demon decides to risk expending a couple points of Essence, and make sure that happens?
Unfavorable Interventions, like favorable ones, shouldn't be overly dramatic except when the GM needs a dramatic moment; otherwise it begins to feel like God and Lucifer are spending entirely too much time zapping individual angels and demons. Interventions will generally be appropriate in severity to the importance of the action that triggered them. Getting an unfavorable Intervention while trying to make your Area Knowledge roll will usually just get you hopelessly lost. It might cause you to run out of gas in front of an enemy Tether if God or Lucifer really feel like screwing with you. But it rarely causes your engine to explode, or "misdirects" you from Los Angeles to San Francisco. (If it does, then maybe finding the nearest convenience store was a lot more important than you thought . . . )
Most unfavorable Interventions fall into one of the categories below. These are only rough guidelines; an unfavorable Intervention can be literally anything bad the GM can come up with. It can be more than one bad effect, in any combination, and at any level of severity the GM thinks appropriate.
The most common type of Intervention, misfortunes are simply harmful "coincidences." They may be small and irritating, or absolutely disastrous. They are rarely overtly supernatural, and the character may not even realize that his "bad luck" was actually the result of malign cosmic fate. Misfortunes are how God and Lucifer stick out a foot to trip the unwary, and usually occur when least expected, during noncritical scenes . . . though they can also happen in the middle of combat.
Most often occurring when someone is attempting something Higher Powers really don't want him to accomplish. An exacerbation is a normal failure . . . amplified. The effect will be at least as bad as a normal failure with a check digit of 6, and may have additional deleterious effects.
This type of Intervention comes in the form of assistance to the character's foes. It happens most often when the character is facing someone on the Other Side. The character might not even see the results; the GM simply uses the Intervention as an excuse to give the character's opponents a free gift; maybe some extra Essence, or a weapon, or knowledge they wouldn't have otherwise had.
A more direct form of Intervention, Interference means someone inimical appears up to harass the character. It might just be a mortal showing up at the worst possible time, with no knowledge of his role in the greater scheme of things, or it might be reinforcements sent expressly to kick the character's butt. Whoever arrives, it will make things worse for the character.
Somebody Really Doesn't Like You. God and Lucifer rarely intervene directly in the War, but when they do, it's unmistakable. God's Avenging Fist (or the Hand of Satan) reaches down to slap you around. This form of Intervention is rarest, and scariest.
Any of the above Interventions can happen at any time, to any degree. Interventions range from trivial to earth-shaking. As a general rule, the GM should make them appropriate to the situation; a gang of Malakim isn't likely to descend from Heaven just because an Impudite failed to charm a random mortal morsel, and someone who rolls an unfavorable Intervention during a confrontation with an enemy Superior should suffer more than just tripping over his shoelaces. However, there are no rules for this, and the GM can make any Intervention so subtle as to pass unnoticed, or a calamity of Biblical proportions.
Trivial Interventions don't disrupt events significantly, and are rarely recognized for what they are. Something unfavorable happens, but it's neither disastrous nor unnatural. This is recommended for when someone happens to roll an Intervention on an unimportant die roll.
Minor interventions are likely to occur during important, but non-critical moments. They can cause great inconvenience, but usually nothing the character can't recover from, with enough determination.
Major interventions occur during critical scenes, such as when a life is at stake, or at a major turning point in the adventure. Combat often falls into this category. Unfavorable Interventions will be dramatic, and usually have a decisive effect . . . the unfortunate recipient will be lucky if he's able to walk away.
A critical intervention occurs during decisive events which can impact the future of the War. An intervention rolled during the climax of an adventure may be of this caliber. The results will probably have a major and permanent negative impact on the character.