How Do I Build This? (Graviton Pulse Field/Graviton Surge)

[DoctorJerk]

Wow, thanks for taking time to think about all that! Seems well-reasoned and fair towards the point value, given the utility and severe limitation imposed by the falloff described in Explosion or Dissipation for abilities that don't also generate Fragmentation or Hot Fragments damage. I wasn't aware of the incidental fragmentation rules, so that helps too. All in all, I found the point cost for creating a useful implosion effect that realistically falls off with distance (or that affects a useful radius) far exceeds the point cost for simply creating near instant-kill or instant-incapacitation abilities. Varyon's ideas sound fairly balanced, so far.

Something else to consider for an attack of this nature are these optional limitations: http://forums.sjgames.com/showpost.p...7&postcount=12

Bonus question 1: I found the rules concerning contact explosions and explosions in enclosed spaces (B.415) and saw that there are rules for multiplying damage by up to 3x or automatically applying maximum possible damage on your available dice. Perhaps, given that implosions and gravitational attacks aren't well covered or easily described in GURPS, how fair would you say it'd be to apply one of these modifiers, or something like them, in this particular case? As far as I can tell, Explosion's damage falloff is calculated based on the idea of an attack that generates single-pulse forces reliant on the physics of a 1G, Earth-like atmosphere or the behavior of ordinary forms of matter/energy like light or fire. Perhaps the damage values for a purely kinetic ("passively kinetic"?) ability like creating a gravity well should be tweaked?

Bonus question 2: If you were the GM and you allowed a gravity-based ability like this, how would you handle the fact that targets with higher mass are gripped tighter by gravity and have more inertia/momentum to overcome? Would you consider the target's ST or HP or anything else, and somehow apply that to the attacker's damage roll?

[Varyon]

Originally Posted by DoctorJerk

Bonus question 1: I found the rules concerning contact explosions and explosions in enclosed spaces (B.415) and saw that there are rules for multiplying damage by up to 3x or automatically applying maximum possible damage on your available dice.

The only effect your explosions have here is knockback, and internal/contained effects shouldn't increase that - if anything, they might decrease knockback. Internal explosions do more damage because every bit of energy they release has to pass through your body, which means it's basically pushing your body in several directions at once; unless you burst, an internal explosion won't really move you much. Contained explosions do more damage because they result in overpressure that surrounds you (instead of just being on one side, as with a typical explosion), which would somewhat hold you in place; alternatively, you can think of it as a wave of damage that goes through you, hits a wall, and bounces back to hit you from the other direction.
Contact is probably OK to increase knockback, but anyone in direct contact with your attack is at the epicenter and thus has nowhere to go, so it doesn't matter.

Originally Posted by DoctorJerk

Bonus question 2: If you were the GM and you allowed a gravity-based ability like this, how would you handle the fact that targets with higher mass are gripped tighter by gravity and have more inertia/momentum to overcome? Would you consider the target's ST or HP or anything else, and somehow apply that to the attacker's damage roll?

Ugh, that's not a pretty situation. Fair warning, this gets complicated. Basically, a "realistic" (but contained) gravity effect wouldn't use knockback mechanics - instead, it would cause foes in the affected area to simply accelerate toward the epicenter at 10x(force of gravity in G's) yards/second/second. If you want to be able to do that, Innate Attack isn't the way to go; instead, you need Control (Gravity), and I'm not a big fan of the Create/Control Advantage from Powers. Actually, looking it up, I don't think Control (Gravity) would work (it only lets you increase or decrease it, not change its direction). So, it would instead be something like Create (Gravity), but there's no guidance on how that would work. My best guess would be to extrapolate from Control. The Medium category for Create seems to roughly correspond to the Common category for Control, so we'll use that, for [20]/level. Control lets you control 10x(level)^2 lb of the matter in question (this will be important for establishing an equivalency), or for Gravity lets you adjust it up or down by 0.1x(level) G's (technically, by 10% of local gravity, but we'll standardize that to 1G) in an area with radius of (level) yards. Create for solids lets you create 10x(level)^2, with the item persisting for 10 seconds (unless you burn character points to make it permanent). That implies Create (Gravity) would allow you to create a localized singularity (albeit one with a small radius) that pulls everything toward it at 0.1x(level) G's, with a radius of (level) yards, and it will last for 10 seconds. This is a potentially quite powerful ability, but is likely to be very expensive - a 1G singularity costs [200] and only has a radius of 10 yards, but it will equally pull a flea, a person, and a dragon toward the epicenter with a 1G (10 yards/second/second) acceleration. Do note that creating a localized singularity isn't the only thing you could do with Create (Gravity) - you should be able to set the gravity to go in a specific direction (up, down, left, right, forward, back, diagonal, whatever), but this wouldn't overwrite local gravity*. Being able to only create a localized singularity (a point that attracts everything within a given radius) would certainly be worth a Limitation, maybe -50% (and that's being rather generous; most of what you can do with the directional effects you can manage with a localized singularity and some clever positioning). Of course, the gravity field made by Create (Gravity) by default has a very short range (one edge must be no further away than adjacent to your character), so you may need to add Ranged, which will boost price back up again.

*This makes things more complicated. Basically, you're generating an additional gravity vector, which gets combined with local gravity to generate the effective gravity. For example, on Earth you have a 1G gravity vector pointing down. If you create a 1G gravity field that pushed north, what you'll actually end up with is a 1.4G gravity vector that points at a 45-degree angle toward north and the ground (making it feel like you're on a 45-degree slope pointing north, and at +40% gravity to boot).

[DoctorJerk]

Originally Posted by Varyon

Ugh, that's not a pretty situation. Fair warning, this gets complicated. Basically, a "realistic" (but contained) gravity effect wouldn't use knockback mechanics - instead, it would cause foes in the affected area to simply accelerate toward the epicenter at 10x(force of gravity in G's) yards/second/second. If you want to be able to do that, Innate Attack isn't the way to go; instead, you need Control (Gravity), and I'm not a big fan of the Create/Control Advantage from Powers. Actually, looking it up, I don't think Control (Gravity) would work (it only lets you increase or decrease it, not change its direction). So, it would instead be something like Create (Gravity), but there's no guidance on how that would work. My best guess would be to extrapolate from Control. The Medium category for Create seems to roughly correspond to the Common category for Control, so we'll use that, for [20]/level. Control lets you control 10x(level)^2 lb of the matter in question (this will be important for establishing an equivalency), or for Gravity lets you adjust it up or down by 0.1x(level) G's (technically, by 10% of local gravity, but we'll standardize that to 1G) in an area with radius of (level) yards. Create for solids lets you create 10x(level)^2, with the item persisting for 10 seconds (unless you burn character points to make it permanent). That implies Create (Gravity) would allow you to create a localized singularity (albeit one with a small radius) that pulls everything toward it at 0.1x(level) G's, with a radius of (level) yards, and it will last for 10 seconds. This is a potentially quite powerful ability, but is likely to be very expensive - a 1G singularity costs [200] and only has a radius of 10 yards, but it will equally pull a flea, a person, and a dragon toward the epicenter with a 1G (10 yards/second/second) acceleration. Do note that creating a localized singularity isn't the only thing you could do with Create (Gravity) - you should be able to set the gravity to go in a specific direction (up, down, left, right, forward, back, diagonal, whatever), but this wouldn't overwrite local gravity*. Being able to only create a localized singularity (a point that attracts everything within a given radius) would certainly be worth a Limitation, maybe -50% (and that's being rather generous; most of what you can do with the directional effects you can manage with a localized singularity and some clever positioning). Of course, the gravity field made by Create (Gravity) by default has a very short range (one edge must be no further away than adjacent to your character), so you may need to add Ranged, which will boost price back up again.

Another case where the cost-effectiveness for a useful ability is far outstripped by SO many other options. Even a 100pt TK and two level of compartmentalized mind would be more flexible and comparably deadly than this. I'm beginning to think GURPS 4e just hates gravity-based abilities lol

Originally Posted by Varyon

*This makes things more complicated. Basically, you're generating an additional gravity vector, which gets combined with local gravity to generate the effective gravity. For example, on Earth you have a 1G gravity vector pointing down. If you create a 1G gravity field that pushed north, what you'll actually end up with is a 1.4G gravity vector that points at a 45-degree angle toward north and the ground (making it feel like you're on a 45-degree slope pointing north, and at +40% gravity to boot).

Sounds about right, but since we're already talking about custom abilities, maybe one could just allow Control Gravity to change the gravity vector of an area? Could do all kinds of useful things with that, as long as you could make a physics and sculpting roll, maybe even some sort of mathematics roll and lightning calculator to make it somewhat realistic and practical for combat.