I'll allow it. This is Star Wars and the rule of cool reigns. Strap those bombs to that droid, but don't forget those red dice! I'd upgrade every check associated with this plan, at least twice.

1. When attacking with a Blast weapon only the primary target is normally hit unless advantage is spent to activate blast, so if blast isn't activated then technically it could be done...(As others have said though here the droid should be making the attack or be forced to be the Primary Target)

Blast weapon yes, but as I read the rules in Dangerous Covenants - Page 54, explosives like detonite, which is what my player is using, don't conform to normal blast weapon quality rules. There are no advantages for more targets with that explosive. It hits everything in range, outright.

Making sure that everyone understands the distinction here. Detonite, attached to droid, droid goes into enemy. Boom. All enemy targets in range automatically hit. Player elects to have the talent mean the explosive avoids the droid...

That's what we're talking here, guys, just to confirm.

Ok, Droid needs to be part of the check somehow. Its not normal to allow a combined check in combat but it may be a solution here. Use the Droids Intellect with the Demolitionists Mechanics skill, no boost for assistance here. The Demolitionist spends an action attaching the explosive, droid spends an action to trigger them. Advantage allow for Selective detonation. The Difficulty could be 2 like a melee check, i would probably upgrade it with a red just coz this is some dangerous stuff going on here.

Thats probably enough to make it doable, but not always ideal due to the 2 actions required; they miss out on doing a lot of other things for the chance to blow themselves up...

Ok, Droid needs to be part of the check somehow. Its not normal to allow a combined check in combat but it may be a solution here. Use the Droids Intellect with the Demolitionists Mechanics skill, no boost for assistance here. The Demolitionist spends an action attaching the explosive, droid spends an action to trigger them. Advantage allow for Selective detonation. The Difficulty could be 2 like a melee check, i would probably upgrade it with a red just coz this is some dangerous stuff going on here.

Thats probably enough to make it doable, but not always ideal due to the 2 actions required; they miss out on doing a lot of other things for the chance to blow themselves up...

The only thing is, my player will claim he can just remotely detonate them, so it doesn't involve the droid's skill.

First answer, No. Second answer, No. Third answer if they somehow manage to convince you . Allright but there will automatically be 2 reds in the difficulty and if either of them comes up despair then the droid is vaporized.

If I were the droid I'd say you go first. If it's safe enough to work on the mechanical then there's no reason it can't be placed on a fleshy one.

I remember joking about this at my last session when I picked up the demo spec.

Surprisingly, I used about 2000 creds of detonite before ever putting ranks into Mechanics, having 2 Int, or even having the demo-spec, and didn't lose any fingers, or party members...and helped speed up a mining process.

Would a "bouncing betty" S-mine style explosive be more reasonable as a model for what the character is attempting to do? The explosive pops out of the top of the droid and then sends out a ring of shrapnel. There would be relatively little force applied up or down, and the droid would be in a comparatively safe zone. There would still be a fireball and a shockwave, but it would be above the droid rather than around it.

The minimal safe zone for the area behind a Claymore is 16 meters. But given those kill ranges, any Star Wars explosives would be far smaller with less back blast.

Rules as written this is perfectly acceptable.

Selective Detonation:

When using any weapon with the Blast quality or explosive device, the character
may spend advantage or triumph to exclude one target that would normally be affected by the explosion.
Multiple targets may be excluded in this manner, but the total number may not exceed his
ranks in Selective Detonation.

The problem of course is eventually he's going to fail to get any advantages or Triumphs and then boom....

Once that happens the problem sorts itself out.

When dealing with despairs and explosives especially with this kind of **** move its always best to have it go off immediately with him still in the blast radius.

How ever using a remote to detonate the charges can go hilariously wrong in so many ways. Jamming can always prevent it from going off or in the case of a despair the droid's own electronics generate the same signal as his detonater. Also give the troopers a perception or vigilance check to notice the explosives they can then disarm them. When his roll comes up with threat you can set a turn delay for how long it takes for the explosives to go off after the signal.

Finally the Astromech droid is intelligent and does have self preservation instincts short of a restraining bolt its very likely to remove them from itself once its out of his reach. Thats if it doesn't run away while he's trying to attach them. Or even worse after he has successfully set the charges with an advantage the Astromech droid sets them off with his arc wielder or shock prod just to prove a point. Just think about what Chopper or R2 D2 would do if someone tried to turn him into a rolling bomb.

Just because rules as written allows it does not mean you can't screw him over while still allowing it.

Excellent. I think you are onto something there. I didn't realise you had to use adv to exclude a target...I hope the player realised...

So why don't use a fire-and-forget-droid like a modified recon remote? Take out the surveilance equipment and the transmitter for the back-channel to the operator and you have a kamikaze-drone for about 400 credits with an encumberance of 1. The effect of my gunslinger with ranged light 4Y throwing normal grenades is worse than this kind of weapon system. There are no stats given for the "mouse-droid" from a new hope but that thing might work as well. The only negative aspect is that you will lose the operating platform if you use it that way, but that would be a by the rules and lore friendly approach to the situation.

Using an Astromech for such stunts is kinda awkward to me as they tend to have a rather stubborn programming and i think there would be no astromech in the entire galaxy that is willing to be converted in a rolling bomb. It's the same thing like shaving a wookie or looking under the cowl of a java or undressing sand people - you just don't do that in Star Wars.