Reverse Missiles / not an "attack"

[RGTraynor]

Originally Posted by ravenfish

This is a tempting reading, but it runs into the problem that, due to air resistance slowing the projectile both coming and going, a strict reversal of its direction would almost certainly fall well short of a shooter firing from anything greater than point-blank range. Unfortunately, this may ultimately be one of those spells that "does exactly what it says on the tin by inexplicable magic"- it works out where the attack came from, and uses the incoming missile for counterbattery fire.

My take is that we need to take into account what the spell's supposed to do, which is to attack the attacker with his own missile. If air resistance was to be a factor, one would expect that the spell would have language along the lines of "Double the range for the purposes of the attacker's 'to hit' roll, as well as assessing any resulting damage."

[Varyon]

Originally Posted by ravenfish

Or, if one prefers to avoid the reducto ad absurdum, what happens if the shooter fires while moving and, when the projectile returns, is no longer where he stood when he fired (unlikely if the projectile is a bullet but potentially quite relevant for a horse archer)?

As I said, and having nothing to do with any question of "intent", the rules-as-written Reverse Missiles spell has some amazing targeting skills.

GURPS ranged attacks are hitscan weapons*, and wherever you are when you make an attack, that's where you are when the projectile returns to you - there is no travel time involved. You need look no further than the penalties for Range to determine this - something that is twice as far away looks half as large, and lo, both situations (twice as far, or half as large) result in the same -2 to hit (you can repeat this for anything else; basically, Range penalties just treat the target as though it were 2 yards away but only as large as it appears... which is exactly how hitscan weapons work).

If you're wanting to get more simulationist than the default, you'll need to make some decisions. How does the spell determine the point of origin, and how is this point fixed in space? Maybe the projectile "remembers" where it came from, and the spell tells it to go back home. The origin point is obviously set relative to the planet (otherwise, with how quickly Earth hurtles through space, I suspect anything beyond point-blank would wildly miss the attacker when it returned), but what else could it be set relative to? A vehicle (so Reverse Missiles still works as-advertised on a speeding train)? A mount (so that horse archer isn't immune)? A shooter (so a teleporting mage isn't necessarily safe.... although I'd argue the projectile should still be subject to 1/2D and Max Range under such a simulationist handling)? What happens if there's something in the way of the projectile returning, that wasn't there when it initially departed? How you answer these questions may well modify how Reverse Missiles functions in your game.

*For those unfamiliar with the term, this is the way projectile weapons work in many - mostly older - video games. When you attack, rather than your weapon producing a projectile that must collide with your target's hitbox to have an effect, the game simply checks to see if your aimpoint is in line with said hitbox when you attack - if it is, the target immediately takes damage. There are some games where there's a visual effect that's slower than the instantaneous damage effect, which can have humorous results - such as a foe falling dead, then being struck by the fireball that killed it (or an arrow fired at an erratically-moving target gaining homing capabilities).

[David Johnston2]

You are allowed to dodge the returning attack.

[johndallman]

Originally Posted by David Johnston2

You are allowed to dodge the returning attack.

However, that requires that you can see it coming, or otherwise be aware of it. This is fine for large, slow missiles, but not for bullets.

[Anthony]

Originally Posted by ravenfish

This is a tempting reading, but it runs into the problem that, due to air resistance slowing the projectile both coming and going, a strict reversal of its direction would almost certainly fall well short of a shooter firing from anything greater than point-blank range [EDIT: I assume, at least- can anyone who knows about ballistics analyze this?].

In a vacuum, reversing path will work unless the attacker was moving (in which case it will wind up returning to the point the projectile was fired from). In atmosphere, it's not going to work correctly for long range fire, but it's probably safely ignorable at normal combat ranges.

[Plane]

I think it the case of shrapnel it would revese back to center of AE rather than where missle was launched, same with a grenade.

[Witchking]

Originally Posted by johndallman

However, that requires that you can see it coming, or otherwise be aware of it. This is fine for large, slow missiles, but not for bullets.

Or worse case scenario; the original 'archer' scores a critical hit with his 'arrow', he gets no defense since the incoming Reversed attack is still a critical hit.

[Witchking]

Originally Posted by Fred Brackin

Multiple attempts to strike a target only come into play if the first attack misses. Reverse Missiles ignores attacks that would miss its' caster.

However with a homing or multiple attack projectile Missile Shield gets to a comedy level. A bullet with such properties fired on a called shot head would FREX somewhat resemble an Ioun Stone.

Orbit and Orbit the head, never to strike...

[Varyon]

Originally Posted by Witchking

Or worse case scenario; the original 'archer' scores a critical hit with his 'arrow', he gets no defense since the incoming Reversed attack is still a critical hit.

A Critical Success should never be detrimental to the character rolling it. In this case, at worst I’d have the reversed missile wind up missing the attacker. I’d honestly be tempted to have something like a 1/6 chance of it bypassing the shield and perhaps a 1/6 or 2/6 chance of getting deflected into another target; in either case, there would be no roll on the Critical Hit Table.

[David Johnston2]

Originally Posted by Witchking

Or worse case scenario; the original 'archer' scores a critical hit with his 'arrow', he gets no defense since the incoming Reversed attack is still a critical hit.

No, it isn't. Actually I'd argue that a critical hit would at the least be a guaranteed miss by the Reverse Missile spell because critical hits mean you got lucky.