Age of Sigmar/Tactics/Old/Order/Ironweld Arsenal

Literally every single Warmachine from Dwarfs and Empire model range folded into one army. Given their lack of other units outside 2 relatively fragile Heroes, it's clear that this is to be combined with other armies like the Freeguild to 90% reform pre-Grand Alliance Empire or Dispossessed for Dwarfs.

Warscrolls

Heroes

• Cogsmith: Dwarf/Duardin Engineer. Comes with a Dwardin Pistol and a Grudge Raker (D3 -1 rend attacks). Can repair a single warmachine within 4" for 1 wound.
• Gunmaster: Human Engineer. Has more decent ranged options than the guy above with all of his ranged weapons being rend -1 and he hits on 3+, but is utterly pathetic in close combat. Speaking of his ranged options, if no enemy units are within 3" of him, and he didn't move, he re-rolls 1s to hit on his weapons.

Warmachines

• Cannon: Ah, the famous cannon. If 2 or 3 Crewmen are within 1" of the Cannon, this thing fires 2 shots that do D6 wounds. If you're incredibly lucky, you just dealt 12 wounds. As always, an excellent unit.
• Helstorm Rocket Blaster Fun to use and scary as hell when you realize how much damage it can potentially do with D6 damage with a full crew. Uses Ork mentality of MORE SHOTS IS BETTAH BOSS as they hit on 5+ so i would recommend taking 2-3 of them if you want to. Nerfed in Ironweld rules, as according to the free PDF an Engineer no longer grants re-rolls. (EDIT: There is a second page that's visible in the APP that gives the rest of the old rules back)
• Helblaster Volleygun: Nerfed in the Ironweld rules. Now all it does is D6 shots that hit on 5s, 4s, or 3s depending on how many crewmen are next to it (5s for 1, 4s for 2, 3s for 3). (EDIT: There is a second page that's visible in the APP that gives the rest of the old rules back)
• Organ Gun: The gambling gun. Its profile is at first underwhelming, being D6 Irondrake shots, but the trick is that you can decide to shoot it up to 4 times. Then, you roll a D6 and if you roll under the number of times you fired it (so, 1-3 if you shoot four times), it jams and you don't fire at all. At peek efficiency, it fires 4D6 Iron Drake shots, up to 24 and still 14 on average, but that gives it a 50% chance of not firing at all. In an Engineer is closeby, you can reroll this jamming test, giving you a 75% chance of it working at peek efficiency and an 88% chance of working with 3 barrels. Yeah, Engineers are awesome.
• Steam Tank Seems too random and weak for its reputation at first, until you realize that with his ability you re-roll ALL of his random values, which makes it very threathening both at range and in close combat, specially against units with 10+ models. Get one or two Mages with the Lore of Life close to this thing, heal it each turn so its performance doesn't decay, and you won't fear anything. After all, who needs monsters when you have TANKS?
• Gyrocopters: Well, the Gyrocopter is supposed to be a mobile gun platform and it is. It's mobile, it's pretty tough, only they sort of forgot to give it a good gun. It's Brimstone Gun pours out three Irondrake shots (woohoo). It's Steam Gun is potentially hilarious. You pick an enemy unit and get one shot for every model in range, though that range is 6", so you'll get at best one salvo before you get stuck in melee. However, three of them stuck in melee can erase entire units with their Steam Guns. They're also some of the most overpriced models GW has ever made, so have fun getting those three. Once per game, they can also drop their bombs, which will, on average, result in one mortal wound per Gyrocopter. Yeah. If you have 3 with Steam Guns, they're hilarious, resulting on average in one wound for every model in range, but otherwise, skip, dorfs have way better war machines than this.
• Gyrobombers: A tougher Gyrocopter who forgot to put a good gun on it because it was too busy fitting bombs to its hull. Its gun is pretty much four Thunderer-shots. It can also drop bombs every turn and they're better than what the Copter has, dealing D3 mortal wounds instead of the two individual rolls. However, since they only hit on 4+, you'll need at least two to have any sort of reliability for your bombs. The biggest shortcoming of the Gyrobomber is its 12" movement, which while fast for Dwarfs, isn't too great, especially since you must be able to completely fly over the enemy unit and clear it by 3" to be allowed to move over it. Sure you could run, but what about your awesome gun? Also, the way the bomber works usually leaves it stranded way off from your main force, far away from any buff your dorfs rely on for survivability.

Battalions

• Artillery Detachment: Take one of each of the above units (that's right all of them) and for all that you get the following: During your hero phase you select an enemy visible to one of the engineers, then roll a dice for each of your other battalion units. On a 6, they can shoot that at the enemy as if its the shooting phase. The total cost is 1280. If all the choices were superstars, then this might be ok. But as is, it's a lot to sink into an army for such a random buff.

Allied Armies

• Freeguild: Arguably the fluffiest and best choice. It's already defensive and ranged, and this just gives it more horde-killing and monster-killing options.
• Steamhead Duardin: See above.

External Links

Rules are here

https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/aos-warscroll-duardin-cogmsith-en.pdf

https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/aos-warscroll-gunmaster-en.pdf

https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/aos-warscroll-duardin-cannon-en.pdf

https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/aos-warscroll-helstorm-rocket-battery-en.pdf

https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/aos-warscroll-helblaster-volley-gun-en.pdf

https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/aos-warscroll-duardin-organ-gun-en.pdf

https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/aos-warscroll-steam-tank-en.pdf

https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/aos-warscroll-duardin-gyropcopter-en.pdf

https://www.games-workshop.com/resources/PDF/AoS_Warscrolls/aos-warscroll-duardin-gyrobomber-en.pdf