Canceling Conditions for Extended Duration Enhancement?

[Pursuivant]

Is there an official method of reducing the value of the Extended Duration enhancement if outside events can cancel it or reduce its normal duration?

For example, is there a RAW way to model the power to turn people into frogs for 4+ hours (call it Affliction, Extended Duration, 300x, +100%, other details don't matter) where exposure to moonlight makes the effect wear off after just 2 hours (dropping Extended Duration to ~30x, +80%)?

Is there a RAW method to model a power which allows you to turn people into frogs for 4+ hours but splashing the victims with holy water cancels the effects immediately?

If there isn't an official method of handling such situations, I'm inclined to use the following house rules:

If a triggering condition reduces maximum duration: Reduce the overall enhancement cost by (higher value - lower value)/2 (round down to the nearest 5%) + lower value for a common or very common triggering condition that reduces duration.

For example, if your frogging power with 300x duration goes to 100x duration (+100% to +80%) if victims are exposed to moonlight (a common situation), modified cost of Extended Duration is (100%-80%)/2 + 80% = +90%.

If a triggering condition can prematurely terminate a power's effects: Multiply the base enhancement cost by 1/4x for a very common condition or multiple common conditions, 1/2x for a common condition or multiple uncommon ones, or 3/4x for an uncommon condition or multiple rare ones. There's no point break if duration is only canceled by a rare condition. Round up to the nearest 5%.

For example, if a power which normally has 300x duration is canceled by an uncommon situation (e.g., the touch of holy water), the Extended Duration enhancement is modified to be worth just +75% (+100% x 3/4). If it's canceled by a very common condition (e.g., exposure to a steady breeze), it's worth just +25%.

Effectively, this is modifying the Extended Duration enhancement with an Accessibility Limitation ("Not in the presence of X" or "Doesn't Work on Y") or the "Weakened by X" limitations.

[Varyon]

Considering Permanent is +150% if a "reasonable" method exists to end the effect or +300% if no such method exists, I think your idea of 1/4 price for Very Common, 1/2 price for Common (which would fit the "reasonable" method's price), 3/4 price for Occasional*, and full price for Rare, should be acceptable (and only applying it to the levels of Extended Duration that get cut off by the "cure" works just fine as well).

*I personally like the Uncommon label better (in no small part because I frequently misspell Occasional), but RAW is Occasional, just in case anyone is confused by your nonstandard nomenclature here.

[Christopher R. Rice]

Originally Posted by Pursuivant

Is there a RAW method to model a power which allows you to turn people into frogs for 4+ hours but splashing the victims with holy water cancels the effects immediately?

This is Terminal Condition (GURPs Powers, p. 112) I think.

[Pursuivant]

Originally Posted by Christopher R. Rice

This is Terminal Condition (GURPs Powers, p. 112) I think.

So it is. Thanks for the pointer.

That means the "Power Immediately Canceled by X" is just Terminal Condition. The limitation isn't granular enough to allow for fine distinctions regarding terminating conditions.

Too keep it consistent with Terminal Condition my notional "Power Duration Reduced by X" modifier needs to be reworked. Call any reduction in duration due to an Occasional/ Uncommon or better trigger as a -5% reduction to standard Extended Duration or a Common/Very Common trigger as a -10% reduction. That keeps limitation values relatively close to those of the Terminal Condition limitation.

[Christopher R. Rice]

Originally Posted by Pursuivant

So it is. Thanks for the pointer.

That means the "Power Immediately Canceled by X" is just Terminal Condition. The limitation isn't granular enough to allow for fine distinctions regarding terminating conditions.

Too keep it consistent with Terminal Condition my notional "Power Duration Reduced by X" modifier needs to be reworked. Call any reduction in duration due to an Occasional/ Uncommon or better trigger as a -5% reduction to standard Extended Duration or a Common/Very Common trigger as a -10% reduction. That keeps limitation values relatively close to those of the Terminal Condition limitation.

Yeah, that tracks.