It would be be using the vehicle rules to shoot at the characters with vehicle scale weapons (so based on SIL of target and weapon range category, in this case CLOSE). Remember that some vehicles actually have personal scale weapons to negate the SIL issue, but then have the same range issues of personal scale combat.

In theory any cover or defense modifiers the PC have would apply against the attack, in the same way shields would. The PC's can also use talents, so dodge could upgrade the difficulty for example.

If the PCs shoot back, I believe you actually decrease the difficulty to shoot at the AT-ST in this case (it is big, so easier to hit, not harder). Of course they wont do much unless they have gunnery weapons or some kind of breach weapon.

Also bear in mind that if the Vehicle weapon hits the soldier (as per the normal rules), each point of damage is actually 10 wounds (so very dangerous). I use a variant rule from the AoR beginners boxed set, so that it only does the damage that result from the roll (normal damage with successes, but without the x10 modifier), but inflicts and automatic critical wound and ignores soak. This way PCs can survive being hit, but probably not for long.

I'd do the latter. The PCS need the break because if they're hit they're going to be evaporated.

I agree with Ferretfur. Use the vehicle rules (in their entirety) when shooting a vehicle weapon and use the personal rules (in their entirety) when shooting a personal weapon. In your example, the AT-ST faces a Hard check while the PCs face an Average check (the AT-ST is 2 Silhouette more than the PCs so the difficulty to attack is lowered by 1).

Hehe two reply and two differents choices :-)

I tried to simulate an encounter btw an AT-ST and a Rebel commando. The scene starts at extreme range. The AT-ST is piloted by a guy from the Vehicle Corp, a rival with 3 AGI and skills Gunnery and Piloting at 2. The gunner is the standard gunner, a minion with all stats at 2 and no skill on his own.

The terrain is a light forest (1 setback die). They are patrolling the area after reports of Rebel activity.

Imagine after initiative roll the slots are like this : Npc, Npc and Commando.

The Rival pilot goes first. He maintains the AT-ST speed at 1 and use the "drive maneuver". I wouldn't bother rolling a piloting test on this one. At speed 1 he could move within close range of a target so I assume the AT-ST can move from extreme range to medium range of the Commando. They are just heading south and the Commando is on their way.

Now my question, how would you simulate the 2 Imperials actively looking at hidden Rebels?? Should they spend each turn an action to roll a Perception check against the Stealth of the Commando? Do the AT-ST has systems to help them like sensors etc

Generally perception vs stealth. You could do this from one of two (maybe three) directions:

1) The Commando (the PC i guess) makes a stealth skill test with the difficulty equal to the highest perception score of the opponents. If they succeed, then they are not spotted (I would usually go with this as the PC is the main character).

2) The Imperials in the Walker could instead make a perception skill test using the Stealth rating of the Commando as the difficulty, and if they succeed, they spot the rebel scum. If the Imperials are NPCs though, it takes away from the player a little.

3) While not technically the rule of law for this kind of test, you could also opt to make it an opposed test, with both parties rolling their skills and see who gets the most successes, but i would not generally do this for stealth.

You should only use one of the other options, not both/all.

Things like trees or bad weather would add boost dice to the stealth roll, though anything the imperials have to see better (such as hunter goggles) could in theory and setback dice or reduce boost dice (and visa versa if going with the perception roll).

Ok that's what I expected to do. Actually the minion gunner would use the assist maneuver and next the Pilot rival would roll the perception check with a boost, and maybe another boost for googles, all that against the stealth of the commando as difficulty plus one setback die for the terrain/cover.

Now that bring us to my second and last question. Maybe not a real question, but.. Finally the commando remained unoticed and fire his missile tube at the AT-ST. He succeed with 2 success, not bad. The base damage is 20, so that's a 22 total. The AT-ST has 3 armor points, minus 1 because of the Breach quality of the missile tube.

2 armor points suck 20 damage points right? So we are left with 2 damage against the 15 hull points of the AT-ST...

**** something is wrong no? The walker took the missile in the face with just a little scratch on the paint... what's wrong?

Nothing, from a certain point of view. Firing from long range with the objective of just hitting the walker in general might not be good enough. Getting up close and blasting the same missile into the engine (or better yet, the viewport) will probably have much better results than simply laying into the front armor.

The rules are exactly the same if I fire at short range or extreme range. Maybe you use custom rules but hitting the engine can only be possible with a critical hit.

1 hour ago, Rosco74 said:

2 armor points suck 20 damage points right? So we are left with 2 damage against the 15 hull points of the AT-ST...

**** something is wrong no? The walker took the missile in the face with just a little scratch on the paint... what's wrong?

Isn't that exactly what happened in Rogue One ?

3 hours ago, Ferretfur said:

3) While not technically the rule of law for this kind of test, you could also opt to make it an opposed test, with both parties rolling their skills and see who gets the most successes, but i would not generally do this for stealth.

Nitpick for reference reasons: The check you want here is called competitive check. 1 and 2 were both opposed checks. They are on page 32 and index of the A-CRB, etc

For the rules and hitting the engine: The rules suggest critical hit like effects when using the aim maneuver. So yeah, aiming for a critical component to temporary knockout a system component sounds reasonable. Mind you, this is not a real critical hit, just a malfunction of the system, a mechanic check should resolve the issue, though depending on the narrative this might force a guy out of the AT-ST, which opens up another attack angle.

Lastly: As long as you do at least as much damage as the vehicle has armor, you can always crit the thing, if you combine it with an aim maneuver and 2 setback dice on the shot … here you go with a critical component hit, one of free choice in this case, which sounds btw a lot better than pseudo crits just from aim.

When you’re seriously out-gunned by vehicle-scale weapons, it has been my experience that your only real hope is to use the Aim maneuver to do a “called shot”, and double-aim if you can so that you get only one setback die. Then carefully choose what part of the vehicle you are shooting at, so that you can disable it before it can shoot at you.

In the case of a smaller vehicle, you might be able to make that called shot against the pilot, or an engine, or a leg, etc….

In the case of a larger vehicle, you could target the bridge and then you would use the rules for getting a critical hit on the bridge if you succeed. That would mean they can no longer do any Maneuvers on their own, nor can they fire any weapons.

Yes, I have been there, and have done that. And managed to survive — So far, at least.

11 hours ago, Rosco74 said:

Now that bring us to my second and last question. Maybe not a real question, but.. Finally the commando remained unoticed and fire his missile tube at the AT-ST. He succeed with 2 success, not bad. The base damage is 20, so that's a 22 total. The AT-ST has 3 armor points, minus 1 because of the Breach quality of the missile tube.

2 armor points suck 20 damage points right? So we are left with 2 damage against the 15 hull points of the AT-ST...

**** something is wrong no? The walker took the missile in the face with just a little scratch on the paint... what's wrong?

Only thing wrong is your certain point of view.

Taking on vehicles with man portable weapons is tricky because it relies on crits and component hits, not Hull Trauma. As long as you beat the armor you can do either, no Hull Trauma required. See spending advantage or triumph in Vehicle combat for details on component hits.

So the Commando's roll was actually trash. Now if he also rolled two triumph, or a triumph and a pair of advantage or something, them he might be in business.

Taking on an AT-ST with a missile tube is kinda like taking on a modern main battle tank with an RPG. It can be done, but it's not a position you want to intentionally get into.

Ok I see the points now, thanks for your help guys

I will reas again adv and triomphs tables to check all opportunities, and the called shot option ..