2: roll your attack pool VS the first target.
Vs the first GROUP of targets.
With shotguns you aim in the general direction of multiple targets, then you pull the trigger and then you will hit all of them at once with pellets from one single shell.
If you aim in the same general direction of one single group of targets when firing all 3 shells in the SA burst then you treat them as one single group of targets and you resolve it step by step just like I highlighted above. Which was the OPs original question.
With a SA burst you also have the option to aim in the general direction of one group of enemies, pull the trigger once, then aim at a second group of enemies and then pull the trigger a second time and then you aim in the general direction of a third group of enemies and pull the trigger a third time. Just like before this is resolved with the "Fire Long Burst or Semi-Auto Burst" Complex Action but unlike the above example you also need to use a "Multiple Attacks" Free Action (and you typically only have one per initiative pass which mean you typically cannot do this while running or while calling a shot etc). And you need to split the dice pool as evenly as possible between the three attacks / between all three groups of enemies. In this scenario all 3 groups also need to be within short or medium range and you also need a weapon skill (not total dice pool - and, depending on your reading, also not including specialization) of 5+. This is the scenario that you highlighted Reaver.
If you wish to attack the same target (one single group of enemies in case of shotguns) more than once then you can for example wield two weapons. Aim them both in the general direction of the same group of enemies and pull both triggers at once. This is resolved with the "Fire Semi-Auto, Single-Shot, Burst Fire or Full-Auto" Simple Action together with the "Multiple Attack" free action. You need to split the dice pool as evenly as possible between the two weapons, but in this case the target (or group of enemies) doesn't have to be within short or medium range and you only need to have a weapon skill of 3+. Also take note off-hand modifiers and the effects of recoil.
Attacking the same target (or single group of enemies) more than once (with firearms, melee weapons or a combination of the two) is an advantage of dual wielding.
Note that everyone does not agree to this reading.
- Some argue that Multiple Attacks is actually Multiple Targets (which it isn't).
- Others argue that you are not allowed to do two attacks in a action phase (which you are - if you for example do them in the same action or if you attack multiple times via interrupt actions).
Multiple grenades are EASY to handle.
There are 3 different triggers that comes into play here.
Grenades that you aim at specific targets and that will explode on contact. You resolve them similar to how you would resolve a regular ranged attack. Target take a regular reaction + intuition test to avoid getting hit. The grenade either hit or miss. If it hit then it will explode on the target with 0 scatter. If it miss then you always roll for scatter and the grenade explode when reaching the full scatter distance.
Grenades that will not explode until the end of the next combat turn (which is sometimes 30+ minutes of combat resolution in real life because of how cumbersome combat with multiple participants in SR5 is). You aim them at a location and they bounce and scatter from there. Often plenty of time to walk away from them before they explode. If target have enough movement left they can spend 10 initiative score to walk over there, take an Agility (2) test to pick up the grenade and then 'return to sender' via a Throw test with a negative dice pool modifier of 2 dice.
And then you have wireless link (also called air burst) grenades. You aim at a location and then detonate them via wireless link when they get close to the location. Often mid air above targets hiding behind cover. They might scatter but the scatter area is typically not that large. If target have enough movement left they can spend 10 initiative score to intercept the path of the grenade, take an Agility (2) test to catch the grenade mid air and then throw them back via a Throw test with a negative dice pool modifier of 2 dice. Targets also have the option to spend 5 initiative score to run (if he have any movement left this combat turn). Target choose direction and distance after the aiming location is announced but before scatter is rolled (you might end up running in the wrong direction).
Is this also true to AOE attacks?
For explosives that detonate on the same initiative score you typically don't take any tests to avoid (except for motion triggered grenades, see above) and you normally only take one single resistance test to soak One combined DV and AP from All overlapping explosions.
This is how you resolve multiple AoE detonations that are triggered on the same Initiative Score
(for example 3 grenades being launched in the same initiative score by a SA grenade launcher)
Calculate ground zero for the different grenades involved (which depend on the grenade triggers, see above).
Calculate distance between each target and each grenade, and by that derive the Damage Value for each explosive.
For each target start with the highest DV and then you add half of the DV of each overlapping explosives.
When it comes to AP, use the highest AP of all overlapping explosives and add 1 for each additional explosive that is overlapping.
Even though there are multiple explosives with different scatter you still treat it as One Single Attack with one DV and one AP for the whole simultaneous blasts for each target within the overlapping blast area.
Note that if the explosion was indoors then you typically also have to consider the integrity of walls and ceilings etc as they will most likely also trigger the 'Blasts in Confined Space' rule. Explosives are kinda lethal in this edition...
