Blood Agent, Reversed

Blood Agent, Reversed is introduced on page 100 of GURPS Pwers under notes for Blood Agent, though P100 didn't at first distinctly name it. It was instead described in the 2nd paragraph using this phrase:
:When Blood Agent works “in reverse” like this
PU8 p 12 is when it finally got the BAR name.
==Prep conditions==
The condition for causing bleeding is:
:"attacker must suffer at least 1 HP of injury from a cutting, impaling, or piercing attack"
Presumably this applies to all kinds of piercing.
Realistically it is possible for crushing/burning/corrosive attacks to also cause blood loss but they are less prone to doing so.
This may require custom rules which convert these damage amounts into C/I/P types.
No Blood is not mentioned but this should probably prevent someone from using an ability like this: they have no ammo. B61 specifies that B420's Bleeding rules are not used.
==Attack conditions==
This is specified:
:"ensure that his blood reaches his target"
This "requires the usual attack roll" which implies that one uses the Innate Attack skill to use one's exsanguinated blood droplets as projectiles, at standard range for the ability.
Aura is an exception: there is no attack roll, but Aura is limited to a Melee Attack range.
Emanation is not listed as an exception but would probably also be, since that normally also bypasses a to-hit roll.
==Continuance conditions==
It is clear that a 1HP injury causes at least 1 attack to be possible for an unspecific amount of time.
To give incentive to make larger injuries, a GM might house-rule for example that you get "attacks equal to HP lost". This would incentivize using higher-ST attacks against oneself, or targeting Veins and Arteries.
It could also be on-concept if using optional Blood Loss rules to allow HP lost to this (except for Internal Bleeding) to generate attacks too.
This could even be used exclusively as the means of providing ammunition for the attack: explaining why characters with No Blood could not use the ability (they never lose HP due to blood loss) and the refernece to cut/impale/pierce could instead refer to those having higher odds of causing bleeding. Basic doesn't explore the mechanics/crunch of that likelihood though later Pyramid approaches to wounding do.
==Halting conditions==
Presumably one could not just keep attacking indefinitely after being injured once in their whole lifespan: you generally eventually stop bleeding and "run out of ammunition", after all. Drawn blood (initially liquid) also has a tendency to dry up and not be flung.
===Disabled by bleeding cessation===
Acidic Blood on P144 phases the interaction with Aura (enhancement) this way:
:Until he stops bleeding (see Bleeding, p. B420), the acid drips on everything nearby.
:the user can deliberately attack others by flicking his blood around.
The "flicking" idea might mean that actual direct contact is not required. This might mean that Aura (even though the enhancement can't be turned off due to lack of Selectivity) can function like a C-range melee attack (which for Innate Attack does NOT require contact) in a similar way to the Ranged note on P105:
:Ranged doesn’t prevent an advantage from working the usual way (in an area around the user or by touch, as appropriate) when the wielder wishes.
===Disabled by time===
Trigger by comparison has an activation period of one minute, which could be a reasonable duration by which to require an attack before exsanguinated blood dries up.
This is different from the time it takes to stop bleeding which would be variable on HT rolls and modified by stuff like Hemophilia.
Certain environmental conditions (moist or dry air, anti-clotting factors) might plausible alter the "drying time" of droplets in ways unlike "Trigger"'s fixed 1-minute condition works for Trigger: Injury which is explicitly not the same (or necessarily implied to be included as part of) BAR
===Disabled by environments===
"GM may rule that such attacks simply don’t work underwater or in other environments where blood would be diluted or washed away"
===Disabled by attacks===
This might plausibly include area effect attacks defined as liquid, like hitting someone with a Crushing Attack defined as a wave of water that would wash off blood droplets someone had prepped in their hand.
A generous GM might allow these to continue until (using the optional Blood Loss rules) a HT check represents a halt in blood loss.
If that is the case, the -40% sort-of has the -15% for Trigger: Injury built into it, though not literally (see "disabled by time" above).
==Pricing==
This is worth -40%. It is worth the same as Only through those who have tasted his blood. The difference is that the former requires someone to touch your blood immediately before it affects them, while the more restrictive taste presumably applies to anyone who has EVER tasted your blood, no immediate amount needed.
"Those who have tasted" vs "those who are actively tasting" distinction could be like Delay version Triggered Delay.
==see also==
*Sense-Based (Reversed)
Category:Limitations