Plot-sensitive power limitations

[Devon]

How would one generally handle limitations to suit special defenses against ordinarily uncommon special effects which suddenly become a real threat?

To wit, a villain gets the power to manipulate a force which is, in most cases, a -1 to -2 limitation. Defenses against this particular effect are cheaper because it's just not that common.

Suddenly that force becomes a daily threat for the PCs, who then start designing spells to counter it, for example, "Desolid -- only vs. this effect". Could be strange radiation, could be temporal flux, something which can generate a wide variety of special effects, necessitating the "Desolid"" approach for defense.

Should the limitation (only vs. this effect) be contextually devalued because of the current plot situation (effect USED to be rare, but now it's a common threat, so you only get a -1/4 or -1/2 limitation), or should it be valued in the context of the entire campaign, especially if the PC's quest is to eliminate the very threat this force would cause?

Any GM advice would be welcome,

- Devon

[austenandrews]

I'd stick with the original value. It's not as if the players are exploiting a loophole or anything. The GM is the one who has decided to turn a rare occurrence into a daily event. If you devalue the Limitation, you wind up with (a) overcosted spells when the current scenario ends and/or (b) spells inconsistently costed from before, during and after the scenario. The only way I can see that being reasonable is if all magic is bought through VPPs (and even then you get the inconsistency issue -- "Why can I buy Fireball and Desol v.s. Rare Force now, when I couldn't do when the Evil Lord Rare Force invaded?").

If the problem is that the PCs can buy these spells too easily, and that reduces the effectiveness of the threat, you can always compensate in-game. Maybe the Evil Lord Rare Force has clouded the magical currents such that his enemies can't invent counterspells without great difficulty. Maybe he's got spells specifically designed to counter the counterspells (like Dispel v.s. "Desolid v.s. Rare Force").

-AA