The Grenadier is the guy that enables everyone else to be more effective. Their starting job is cover destruction, which is super important. Later in the campaign they can get Incendiary Grenades, Bluescreen Bombs, and Sting Grenades making them the true multitool class, having an answer for every problem. My build for the Grenadier leans into this role, ignoring the ancillary buffs to smoke and action economy in order to maximize the effectiveness of those beautiful beautiful grenades.
Sapper
Heavy Ordinance
Bluescreen Bombs
HEAT Warheads
Sting Grenades
Volatile Mix
Full Kit
Sapper:
This is a critical ability, turning your unreliable cover destruction into very reliable cover destruction. This is why we bring a Grenadier on missions in the early game. This is their core responsibility, and it is incredibly important. That being said, even with Sapper, you cannot expect a grenade to blow up sturdy cover.
Alternatives: Needle Grenades or Rapid Deployment.
The Needle Grenades ability is seldom going to matter. Most often a grenade will blow cover without killing the target. But even if it is killed, there may not be loot. And even if there was loot, it may have been bad loot. And even if it was good loot you will get it later on. Your soldiers are more valuable than loot, anyway. Keep them alive, and the loot will follow.
Rapid Deployment allows the Grenadier to throw a flashbang and then do something else, which is very strong if this Grenadier is an Officer, otherwise not so much. A Grenadier that is wearing plating and picks the Heavy Ordinance ability at corporal rank can only carry 4 grenades/flashbangs. This will be their ordinance limit for several months of the campaign. And during most missions there will be about 4 pods to fight (3 pods on the map, 1 RNF drop in, give or take), meaning the Grenadier can use 1 item of ordinance per encounter. Blowing through 2 items in one turn will eventually leave the Grenadier dry. It is better to get more out of each grenade (with Sapper), than to throw them out faster. Also, early in the campaign Grenadiers should be carrying grenades instead of flashbangs, because of their unique ability to throw grenades a greater distance than other classes. Other soldiers can take a flashbang, which can be thrown much further than a grenade, by everyone who is not a Grenadier.
Heavy Ordinance:
Without grenades a Grenadier is a weak soldier. One extra grenade, is huge. It will be the long and hard missions when this extra grenade is most helpful, and that is when you will need the most help. Later in the campaign, this ability will double the quantity of Incendiary Grenades/Bombs held by the Grenadier, also a big advantage.
Alternatives: Center Mass or Protector.
Protector is exactly the same as Heavy Ordinance except that it adds an extra flashbang or smoke, instead of a damaging grenade, and so it is not as good. Early in the campaign, the Grenadier should carry grenades not flashbangs, and later in the campaign the Grenadier will want 2 Incendiary Grenades instead of 1. If the Grenadier also wants 2 sting grenades you can equip 2 flashbangs in 2 different slots at no additional cost because flashbangs are free. To do so with Incendiary Grenades would require building twice as many.
Center Mass is good on shooters… Grenadiers are not shooters. Center Mass makes the Grenadier a marginally better shooter, but it also means the Grenadier will spend an extra round shooting instead of throwing a grenade, a big drop off in utility for that round, in exchange for a small improvement in later rounds.
Bluescreen Bombs:
With this ability the grenadier can now help the Specialist hack MECs, no small contribution. It becomes an even more effective ability when paired with Sting Grenades at TSGT rank. Bluescreen Bombs will typically improve a hack chance by about 30% But it varies quite a bit depending on the target. Its better against weaker targets. In practice this ability will move your hackable targets up by one tier; from drones to MEC1s, MEC1s to MEC2s, MEC2s to MEC3s.
Alternatives: Boosted Cores or Formidable.
Boosted Cores adds a point of damage to grenades which is ok. The primary purpose of grenades is cover removal and status effects. Damage is good for softening up, but a secondary concern, and one more point of damage is not important.
Formidable is great on any soldier, especially the Grenadier which will want to carry more grenades rather than protective gear. But Bluescreen Bombs are too good to pass up. Instead the Grenadier can add some much needed HP with their PCS slot, seeing as how they won’t need the PCS to do anything else.
HEAT Warheads:
This is one of the weaker Grenadier abilities but still nice. Eventually the Grenadier will have access to Alien Grenades, which shred 2 points of armor, and this perk will make that 3. Only 1 more armor shredded doesn’t seem like much, but against the heaviest armored enemies (Gatekeepers, MEC3s, Sectopods, and Hive Queens) this can be essential. When Kubikiri is not available, it is near impossible to kill these enemies without first breaking their armor. There are better ways to shred armor than this ability but not many. Armor shredding is rare, mostly obtained from ordinance (grenades, rockets, shredder gun). The other 2 sources of shredding are a Gunner with the Shredder ability or the utility slot item Shredder Rounds. Well, also from the AWC but that is not often available to those soldiers (Rangers) who will be able to make good use of it. Gunners are not always included in my squads, as I prefer other classes in the late game. And I rarely equip my shooters with Shredder Rounds, preferring Dragon Rounds, Venom Rounds, and Talon Rounds. So this is an opportunity to acquire additional shredding, and compensate my squad for all the other times I turn it down.
Alternatives: Tandem Warheads or Dense Smoke.
Dense Smoke I have never selected. It is terrible; only a 10% buff, much weaker than in the original Long War, and carrying smoke would replace either an Incendiary Grenade or a sting grenade which are far superior methods of mitigating danger.
Tandem Warheads seems pretty good. Damage is not the primary purpose of grenades, but more damage seems preferable to 1 additional armor shred in most situations, given that most enemies don’t have much armor. If you take a Gunner with the Shredder ability on every mission, or a Ranger with Shredder Rounds (or Shredder from the AWC) then I think Tandem Warheads is the better ability here.
Sting Grenades:
This is one of the best abilities in the game. It is great in every large fire fight but particularly useful against the MEC pods which start showing up in the late game. When faced with an 8 MEC pod, often with 2 Super Heavy MECs, there is almost nothing any other class can do to prevent your squad from taking a beating. Maybe the Specialist can save you with a hack, but he will have a better chance to do so if your first action is tossing a Sting Grenade. This will stun half the pod, disorient the other half, and with the Bluescreen Bombs ability reduce the hack defense of all of them so that your Specialist can cherry pick the best target. Then your other soldiers can kill the disoriented MECs or other enemies, or use Redscreen Rounds on the hack target. Whatever is left of the robots will probably target the turncoat MEC, and you may get away without a scratch. While Sting Grenades do a bit less against non robotic pods, they are still stupid powerful.
Alternatives: Biggest Booms or Chain Shot.
Biggest Booms is not worth considering over Sting Grenades.
Chain shot is not worth considering over Sting Grenades.
Volatile Mix:
This makes a huge difference with Incendiary Grenades/Bombs. It increases the plus symbol blast area (5 tiles) to a 3x3 square (9 tiles) for the grenade. For the bomb it gives a civ city blast area (21 tiles). Sometimes this doesn’t matter at all, as you are targeting a single unit, or 2 targets that are adjacent. But more often this will mean you hit additional enemies. With Incendiary Bombs and Volatile Mix, the Grenadier can deliver a burning ambush almost as powerful as that of the Technical, and from safer range. Volatile Mix will often allow a Sting Grenade to hit additional enemies. It is quite good.
Alternatives: Bombardier or Salvo.
Bombardier is not necessary given that in Long War 2 most enemies are moving towards you. Also, with the advanced grenade launcher the Grenadier can reach most targets, especially when equipped with an SMG for added mobility.
Choosing Salvo has the same trade off as choosing Rapid Deployment; it sacrifices effectiveness for a quicker burn rate. With a limited supply of ordinance this is often a bad compromise. While at this stage in the campaign the Grenadier will have access to more ordinance, those extra grenades need to last longer, as there are missions with more enemies and they have vastly more HP. The better strategy is to maximize the effectiveness of each grenade, rather than throwing them out faster.
Full Kit:
This grants 2 extra grenades when using one utility slot for plating. If you use all utility slots for grenades, it grants an extra 3. It will mean the Grenadier does not run out of ammo until the very end of long missions, and on short missions, it will mean the Grenadier can spend ordinance with utter abandon, or use 2 utility slots for defensive gear.
Alternatives: Combat Engineer or Ghost Grenade.
Combat Engineer will help you destroy sturdy environment objects, but it is still not 100% reliable. More importantly, we are now so far beyond cover destruction. If the enemy is behind high and sturdy cover, then the Grenadier can instead use an Incendiary Grenade or Sting Grenade. Or your shooters can shoot through the cover. Or your Psi Soldier can Stasis the enemy. And so on. We have options.
I have never chosen Ghost Grenade, but it seems like a nice ability. It is a single use item that acts like a smoke grenade, but also grants concealment to a single soldier at the targeted square. 2 uses of Sting/Incendiary are better, especially given that a Shinobi can reacquire Concealment by choosing that ability.