Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

Making a character who's body contains a reservoir of substance it can use to heal itself. When this substance runs out, the character can no longer heal until this substance is replenished.

I thought I could do this by combining regeneration and minor-regrowth with total-unhealing. The total-unhealing would have a treatment-mitigator. This treatment is not based on time, but on number of HP regenerated. The character can only regenerate X HP before total-unhealing activates. It then deactivated with treatment.

Thing is, with my current sources, there's no way for me figure out what the point cost would be!

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

I would use Healing (or regeneration) + Costs Energy Reserve (not Fatigue). This ER would be the "substance". So, when you run out of ER you can heal no more.

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

This sounds right to me.

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

Agree with the above. And then you can cost it based on how easy or difficult it is to replenish the reservoir.

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

The GM would need to come up with a base assumption for how much damage the character is likely to take during, say, a day of adventuring (if this is in excess of your character's healing rate, he'd use your character's maximum healing rate instead). You then set the rate of treatment based on that.

So, let's say the GM decides your character is unlikely to typically take more than 100% of HP* of damage during a day of adventuring, and your character can regenerate at least that much (Regular Regeneration is good for 240% of HP per day). If you have a reserve of 100% of HP, that calls for Daily treatment. If you have a reserve of 1000% of HP, that's right between Weekly (700%) and BiWeekly (1400%), and so forth.

*I typically set each HP of regeneration as 10% of HP - so a character with HP 15 and Extreme Regeneration would recover 15 HP per second, not 10. Makes the jump from HP 19 to HP 20 less extreme. If you prefer to stick with things as-is, the above become 10 HP, 24 HP, 10 HP, 100 HP, 70 HP, and 140 HP, respectively.

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

I apologize. I left out an important piece of information.

This substance does not replenish itself. So this feature is similar to a dependency, except it's not based on time. It can last indefinitely if the character takes no damage. But if it runs out, unhealing activates until the character ingests more.

Using current GURPS advantages/disadvantages and their mods, there's doesn't seem to be any way to do this!

Now, it would be so easy to simply invent this feature. Making these rules is not a problem. The problem is simply figuring out the point cost. According to the setting, Varyon's suggestion of a 24 HP reservoir for regeneration would be ideal.

The character is a class of NPCs called Zoids. Their bio is in the form a dialogue, this being the most important part:

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

Perhaps vitality reserve that doesn't immediately keep you alive is appropriate?

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

Can PC's be Zoids? If not, you probably don't need a point cost. There's a partial exception if a PC can have one or more Zoids as personal Allies or Enemies. In that case, however, you have a bit of leeway with points (keep in mind the GM builds Allies and Enemies, not the player), given such characters are meant to be up to 100% (or whatever level you purchase) of the PC's point value, so if we're a little off in our estimate, it's probably fine.

If you still need a point value, I think the only thing you're missing is the rate at which you expect these characters to accumulate injury while involved in an adventure (you don't need to worry about the ones working on the fringes of space or whatever - those probably just have Doesn't Eat and maybe a Quirk that they need to occasionally consume some Zoidpaste or whatever). Note that, given the large gaps in time per -5% for the Mitigator, you can get away with a pretty rough estimate. You said 24 HP sounded about right for the full reserve, from which I'll assume they have Regular Regeneration and have enough on a full tank to heal for a full day. If you expect them to suffer around that much injury or a bit more in a day (again, a day they are involved in an adventure and/or combat), Mitigator: Daily Treatment -60% works. If you expect them to take less than that, but more than 3 HP injury, go with Mitigator: Weekly -65% (24/7=~3.5). If you expect them to take between around 1 and 3 HP per day, go with Mitigator: Monthly -70% (24/30=0.8). If you expect them to only take less than that, Mitigator: Seasonally* -75% (down to ~1 HP injury every 4 days) or Mitigator: Yearly* -80% (down to ~1 HP injury every 15 days) should work. You may wish to apply the inverse to their Regeneration and Regrowth - arguably, Daily would be -40% on an Advantage, while Weekly would be -35%, Monthly would be -30%, etc. This probably gives an excessively-high discount, however (-30% for having to take a drug once a month is rather high); you may wish to look at Power Ups 8: Limitations for ideas of more proper costs.

Note here we're using the pricing for time-dependent Mitigators. This is similar to how one makes a "Until [event] occurs" Duration in Ritual Path Magic - the GM figures out how long it's likely to take for said event to occur, then sets the cost of Duration based on that. If the GM expects the event to happen in a year, you pay for 1 year Duration - and even if the event doesn't actually happen for decades, the spell stays in effect until it does (or the magic gets dispelled).

*Note I don't think these are RAW, but roughly follow the Day->Week->Month pattern.

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

Until you said that about the Zoids, I was wondering if this was yet another poster trying to play Vampire: the Masquerade but in GURPS! Maybe some of those who've done that could chime in here? Exactly the same scenario, it looks like.

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

Maybe something like Unhealing with a mitigator and Regeneration with a Trigger?

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

PU8 designs mitigators for disadvantages by applying limitations to counters so I think it would be:

Unhealing Partial [-20]
Not Unhealing (Costs ER -10%) [18]

In this case 1/minute is way too high a cost to be useful for standard healing but if you have a per-minute Regeneration atop this it would be fine.

Actually maybe another way would work... PU8p5 has "only while using (ability)" as -10% so applying this to either Regeneration or Not Unhealing could work.

It feels like cheating in some way to do this though... at least for passive abilities with essentially no detriment to keeping on. Stuff like "only while flying" is a drawback because flying is obvious and shows you're a superhero.

Given the text "neither can have a Link" to me this implies pretty strongly that both abilities need to be switchable, so you would need to take Switchable +10% on both Regeneration and Not Unhealing to be able to take a "only while using X" limitation.

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

Any sort of "only while X" limitation on a normally always on ability without anything else that makes it switchable makes it function as always on any time the X criteria is fulfilled. You only need Switchable if the power can be toggled on and off while the criteria is fulfilled.

For example, Extra Arms (Only while playing piano, Switchable) means you can choose to have extra arms while playing the piano, while Extra Arms (Only while playing the piano) means you can't play the piano without sprouting extra arms.

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

Note on Terminology: I didn’t know Zoid was already a franchise. I used Google Translate to find a Greek word meaning "likeness of a life form." I renamed the creature to Prosoid, meaning "likeness of a person." The NPCs are now called Prosoids.

I think I've figured out how to do the point cost! I want you to tell me if it's all sound.

I got it from the point costs of what I like to call 'hyperbolic-advantages': unlimited versions of leveled advantages—Extended-Lifespan vs Ageless, Fearlessness vs Unfazeable, etc.

In both cases, the hyperbolic-advantage costs 8x the leveled advantage. If we treat Regeneration as a hyperbolic-advantage, then you could turn it into a leveled-advantage costing 1/8 its points per level.

So how many HP per level can you regenerate? If a hyperbolic-advantage is unlimited, then Regeneration should save you from certain death—in theory, not practice! That's 6x HP at level 8—the point at which the hyperbolic-advantage becomes more economical. 6/8 is 0.75 = you are limited to regenerating 75% of HP per level.

This would put leveled regeneration at...

Level 1: 12.5% point cost: 0.75x HP
Level 2: 25.0% point cost: 1.5x HP
Level 3: 37.5% point cost: 2.25x HP
Level 4: 50.0% point cost: 3x HP
Level 5: 62.5% point cost: 3.75x HP
Level 6: 75.0% point cost: 4.5x HP
Level 7: 87.5% point cost: 5.25x HP

Just apply these values to Regeneration under the limitation Mitigator: Cached-Treatment. "Cached-Treatment is a drug or treatment you take that does not expire with time. Instead, it is used up by the action of the advantage, and thus has its own value you need to track. In the case of Regeneration, said value is the number of HP that can be regenerated before needing another treatment."

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

This is the way to go, and acquiring a substance to replenish your ER would be a special recharge limitation.

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

another idea might be to take "Aftermath: Unhealing" which is 1/2 the value it'd be as a Temporary Disadvantage, and lasts 10 minutes or however long you had your Regeneration on, whichever is longer

To do this you would need some kind of limitation on how long Regeneration stays on to, like Maximum Duration.

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

Could this be a weird vitality reserve? That might be the simplest way to represent it

Re: Regeneration + Mitigated-Unhealing based on Number of HP Regenerated?
 

I think you're making some flawed assumptions. Any level of regeneration can regenerate infinite hit points and the lesser form of an absolute advantage does not always fit the 1/8th scheme.

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How fast is the healing process when they have access to their "fuel"?

How difficult is the "fuel" to get? Does it take long to fill the "reservoir" when they acquire the substance?

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The simplest way to do this is to take Unhealing and then take "Not Unhealing" + Regeneration as a combined advantage and add either Limited Use with Fast Reload or the Trigger limitation on the package to represent the need for the substance.