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

[DoctorJerk]

I have a character capable of transforming into something like an eldritch abomination and I'd like to give it a power characteristic of such creatures. My first thought was to have it create black holes, which is not only tactically stupid and irresponsible, but prohibitively expensive to do, even small ones. So rather than create a permanent hazard that might destroy the planet, manipulating the (theoretical) force carrier particle of gravity on a smaller scale might be more reasonable.

Here's what I have so far:
Crushing Attack (2) [Graviton Pulse Field] (Area Effect (16 yd); Cosmic: Irresistible attack; No Blunt Trauma; No Wounding; Double Knockback, (Feature: Reversed Knockback +20%); Elemental: Gravity; Partial Dice (+2); Persistent; Rapid Fire (+10); Very Rapid Fire) [93]

Here's what I think it does, and what I'd like it to do:
The user specifies an area (+4 to hit) and makes an attack roll. If successfully landing all 10 very rapid fire shots, that one hex is the origin point for a 2d crushing implosive force that repeats over the next 10 seconds, 10 times per second, each set of ticks occurring in the same effective instant, in a 16 yd radius. On a minimum damage roll of 2cr+2cr, victims are subject to a total of 40cr damage (No wounding or blunt trauma) in one second.

Here's what I'm uncertain about:

1) Should the crushing damage be summed before knockback is calculated, or for each tick separately? My hope is that it should be summed before knockback since all ticks in each second occur simultaneously for all practical purposes, thanks to the Very Rapid Fire enhancement (Powers P.105). Otherwise, the ability is virtually useless against enemies with a strength higher than 12 on the very best possible damage roll, unless they're standing in a room full of unreasonably sharp knickknacks. My logic is that if you were hit over every square inch of your body with the force of a hard-chucked basketball, it might not move you, but it'd certainly give you a noticeable kick. However, if you were hit with the same force 10 times in the very same instant, its not unreasonable to say that all those forces would add together into one big shove.

2) Does this ability even need the Cosmic: Irresistible Attack enhancement (Powers, P.128)? Could the Elemental limitation cover the desired behavior? The only property I think this version of Cosmic contributes, is the RAW ability for the effect to ignore walls and cover as an obstruction, but I'd be sending it around enemy cover anyway and hitting potential allies behind walls I can't see through is undesirable. Besides, it doesn't actually need to penetrate enemy damage resistance, even cosmic DR, since the goal of the attack is to shove everything in its area of effect towards the center and cause damage through collisions and debris impacts. Perhaps, since the attack is based on the idea of manipulating gravitons, which wouldn't care about walls anyway, would this attack pass through walls without this version of Cosmic? I mean, I want enemies to be able to counter this with anti-gravity tech or abilities, but since those abilities don't seem to require taking a Cosmic enhancement or modifier to have, I don't see why this one should, if it can be countered by non-Cosmic measures.

3) Does the Very Rapid Fire enhancement remove one's ability to determine how many shots to fire? I couldn't get an explicit read on how this enhancement is intended to work. Given that it's an enhancement, I'm thinking it still lets the user choose to fire any amount of shots up to RoF, but all shots happen together, almost instantly. I'm hoping you can still choose how many shots to fire, so this ability can be adjustable in strength.

4) If an enemy is in the center of the area of effect and pressed against another object being affected by this attack, should they take collision damage based on how fast each object would have been moving toward each other? Basically, the victims are being mashed together by a powerful force, surely that should produce a damaging effect.

As far as whether damage should be summed, I found a discussion about a character making multiple attacks, but nothing specifically about the Very Rapid Fire enhancement being taken into account. However, I think the thread indirectly makes a case for summing the damage before calculating knockback: http://forums.sjgames.com/showthread.php?t=87960

Annoyingly, I could find nothing regarding how to build implosion attacks in the books, but I did find a Kromm post regarding the price for reversing the direction of knockback that I found very reasonable: http://forums.sjgames.com/showpost.p...74&postcount=8

So, this all describes a graviton pulse effect that someone can escape if they moved out of the AoE between pulses or passed through within less than a second. How would you model it if you wanted to create an attack that produced a continuous gravitational pull towards a central location, something you'd have to try to resist even if passing through for only a moment? e.g Zarya's Graviton Surge ability from Overwatch

[johndallman]

Originally Posted by DoctorJerk

If successfully landing all 10 very rapid fire shots

What happens if you fail to do this?

[DoctorJerk]

Scatter, of course. There'd be multiple fields of implosion effect and only the overlapping fields might have cumulative effects, but how that plays out would be up to the GM, I suppose. I plan to include an Accurate enhancement and only ever use the ability after an Aim maneuver which, according to my stats, would only ever have any misses on a roll of 17 or 18. I didn't include this for the purposes of brevity and ease of reading.

[DangerousThing]

Originally Posted by DoctorJerk

Scatter, of course. There'd be multiple fields of implosion effect and only the overlapping fields might have cumulative effects, but how that plays out would be up to the GM, I suppose. I plan to include an Accurate enhancement and only ever use the ability after an Aim maneuver which, according to my stats, would only ever have any misses on a roll of 17 or 18. I didn't include this for the purposes of brevity and ease of reading.

Why not just make it a leveled attack with the center at a distance. The number of attacks visible is just a special effect in my version.

[DoctorJerk]

Originally Posted by DangerousThing

Why not just make it a leveled attack with the center at a distance. The number of attacks visible is just a special effect in my version.

I'm not sure what you mean; is there an example power in a book you can point me to, or can you sketch one up with the core modifiers here?

[whswhs]

The basic idea's pretty close to what I came up with, which was a Crushing Attack with an armor divisor of infinity.

[DangerousThing]

Originally Posted by DoctorJerk

I'm not sure what you mean; is there an example power in a book you can point me to, or can you sketch one up with the core modifiers here?

Crushing Attack (5) [Graviton Pulse Field] (Area Effect (16 yd, +200%); Cosmic: Irresistible attack (+300%); No Wounding (-50%); Double Knockback (+20%), (Feature: Reversed Knockback +20%); Dissipation (-50%); 27 points per level.

I removed No Blunt Trauma, because I don't think it is compatible with No Wounding. I added Dissipation.

[ericthered]

1) I'd think that each attack should be calculated separately. Just from a mechanical sense. In gurps you buy the effect of what happens, not the description. If you want them all to be one implosion, they should all be one attack, I'd think.

2) No, you don't need cosmic. Area effect will do all the stuff you need it to.

3) I don't think so.
4) No. You explicitly took No Wounding and No Blunt Trauma. Buy the effect, not the description. If you want the center to be damaging, you can add a linked damaging effect only at the center. I would allow damage from things flying into the center though.

[DoctorJerk]

Originally Posted by ericthered

1) I'd think that each attack should be calculated separately. Just from a mechanical sense. In gurps you buy the effect of what happens, not the description. If you want them all to be one implosion, they should all be one attack, I'd think.

2) No, you don't need cosmic. Area effect will do all the stuff you need it to.

3) I don't think so.
4) No. You explicitly took No Wounding and No Blunt Trauma. Buy the effect, not the description. If you want the center to be damaging, you can add a linked damaging effect only at the center. I would allow damage from things flying into the center though.

Makes sense, thanks for the input! With that approach in mind, seems this sort of ability isn't very cost-effective, but a single, big, continuous area-effect crushing attack with a linked binding effect and constriction damage in its center might be the most efficient the way to go. A TK build could do something similar, but probably for way more points and less tactical flexibility if you don't already have multiple levels of compartmentalized mind.

[Varyon]

First off, I should note that to my knowledge, Area Effect and Rapid Fire aren't technically compatible, you'd need to make the attack Explosive instead (which has some pretty harsh fall-offs with distance, but on the bright side can cause shrapnel damage by default via incidental fragmentation - see B415). I'd suggest Explosive 3, as that has the least-harsh fall-off. Honestly, the Rapid Fire part of it looks a lot like it's meant to be a way to simply reduce cost, but I could be mistaking your intent.

Originally Posted by DoctorJerk

1) Should the crushing damage be summed before knockback is calculated, or for each tick separately?

I have no problem with summing up all the knockback generated by the attack to assess the effect. Arguably, they shouldn't combine linearly like this, but for simplicity it's probably acceptable*. From a game-balance perspective, the primary difference between assessing them separately is that you end up dropping fractions in that case (although there's also velocity to keep in mind).

*Consider two people with ST 12 pushing you, when compared to one person with ST 17 - which is twice as strong by BL - pushing you. Realistically, the two scenarios would result in the same amount of knockback. An ST 12 push averages 5 knockback, for 10 knockback with two people. An ST 17 push averages 11 knockback, which is close enough to be fine. However, for 2xST 17 vs ST 24 (again, twice as strong by BL; note I'm using odd numbers here to get as close to "double BL" as possible), you're looking at 22 knockback vs only 16.
If you want to be a glutton for complication, an option would be to find out what ST score corresponds to the knockback of each hit, then do a sum of squares - that is, square the ST scores, add them together, then take the square root - to get the "combined ST," then use that for calculating knockback. So, for 10 hits from a 2d attack, 2d corresponds to thr for ST 21 or 22; we'll use 21.5. 21.5^2=462.25, or 4622.5 when multiplied by 10. 4622.5^0.5 is 68, which is around 8d-1 (rather than the 20d you'd calculate normally). I'd recommend against this approach, in no small part because it's an attempt to be realistic, but is reliant on the rather-unrealistic ST-based damage table.

Originally Posted by DoctorJerk

2) Does this ability even need the Cosmic: Irresistible Attack enhancement (Powers, P.128)?

The fact it's a knockback-only attack gets rid of the bulk of the benefit of Irresistible Attack - personal DR doesn't matter to those, although Cover DR from intervening walls and the like does. If I were GM, I'd drop the cost of Irresistible Attack to only +50% (and possibly rename it to "Ignores Walls") for this power. If you don't want it to affect your allies (and yourself), I'd strongly suggest Selective Area +20% (or maybe just Selectivity +10%, so that you can turn off "Ignores Walls" when that would be inconvenient).

Originally Posted by DoctorJerk

3) Does the Very Rapid Fire enhancement remove one's ability to determine how many shots to fire?

I see no reason why it would; so far as I can tell, it's really just an Enhancement that reduces Rcl to 0.5, but explains this in a roundabout fashion because non-integer Rcl isn't a thing in GURPS. That being said, the existence of the Selective Fire Enhancement as part of Rapid Fire implies that Rapid Fire normally doesn't let you pick how may shots you take - or, at least, it assumes all RoF 5+ powers have RoF n! if they lack Selective Fire (which means minimum number of shots is 1/4 RoF).

Originally Posted by DoctorJerk

4) If an enemy is in the center of the area of effect and pressed against another object being affected by this attack, should they take collision damage based on how fast each object would have been moving toward each other? Basically, the victims are being mashed together by a powerful force, surely that should produce a damaging effect.

Something at the epicenter shouldn't take actual damage from anything other than other stuff impacting against it. It's a lot easier to hurt someone by shoving them into a wall than by shoving them toward it when they're already right up against it. Arguably, there would be some effect of basically trying to crush them, but this would be reduced compared to the damage from flinging them into walls. If you want to still have there be some damage at the epicenter, an option (albeit a somewhat-complex one) might be to only have No Wounding apply to the Area Effect/Explosive part of the attack and perhaps some of the basic attack itself. Let's say whatever is at the epicenter gets crushed for half the basic damage, but those away from it simply get flung toward the center. Using Explosive 3, you'd apply No Wounding and No Blunt Trauma to that (via the rules for Limiting Enhancements), reducing it from +150% to +30%, and to half the damage of the attack itself, which works out to "Half Wounding" being -35%. Irresistible Attack is no longer justified as being quite so cheap, however; I'd argue that Irresistible Attack applies at full cost to half the damage (which works out to +150%), and I'd just ignore its cost for the other half.

Originally Posted by DoctorJerk

How would you model it if you wanted to create an attack that produced a continuous gravitational pull towards a central location, something you'd have to try to resist even if passing through for only a moment? e.g Zarya's Graviton Surge ability from Overwatch

Give it Persistent +40% - which I see you've actually already done. This is technically only available for Area Effect, but I don't think it would be a problem to let it apply to Explosive as well. It does exactly what you want - anyone who passes through the area is automatically hit by the attack, and those within it are affected until they're able to escape or the effect ends. There is the oddity that it technically lets any character move their full Move on their turn, and then if they didn't escape the pull it yanks them back in, but that's up to the GM to address (personally, I'd let you do your normal Move, then assess the knockback immediately, and decide wherever you end up is actually where you managed to move to, with no yo-yo'ing involved; if the knockback resulted in the character falling, I'd be tempted to have their margin of failure dictate how far they got before losing their balance).

...

All told, your ability might look something like the following. Note enhancing Range (these are all Range 10/100) and Accuracy (these are all Acc 3) will, of course, increase the price.

Innate Attack 5d cr (Cosmic: Ignores Walls +50%; Double Knockback +20%; Explosion 3 +150%; Persistent +40%; Rapid Fire (x10) +100%; Reverse Knockback +20%; Very Rapid Fire +10%; Elemental: Gravity -10%; No Blunt Trauma -20%; No Wounding -50%) [93]

When the attack hits a target, it creates an implosion field at the point of impact. Anything not at the point of impact is pulled toward it, doing 5dx2 of knockback divided by the distance from the epicenter in yards. The implosion field deals no damage on its own, but objects within it may collide for normal collision damage, and if there is any debris around the victims may be struck by it (see incidental fragmentation, B415). The field lasts for 10 seconds.

Alternatively, if you want Area of Effect (so that it affects everyone within a given area equally), you'll need to give up Rapid Fire and Very Rapid Fire, and use the savings for additional damage, although you don't get much.

Innate Attack 5d+1 cr (Area Effect 16 yards +200%; Cosmic: Ignores Walls +50%; Double Knockback +20%; Persistent +40%; Reverse Knockback +20%; Elemental: Gravity -10%; No Blunt Trauma -20%; No Wounding -50%) [93]

If you liked my complicated idea for the epicenter doing some damage, here's the way that build would work, going off of the Area Effect version.

Innate Attack 5d (Area Effect 16 yards (No Blunt Trauma -20%; No Wounding -50%) +60%; Cosmic: Irresistible Attack (Half Damage, Epicenter Only, otherwise Ignores Walls, -50%) +150%; Double Knockback +20%; Persistent +40%; Reverse Knockback +20%; Elemental: Gravity -10%) [95]