Age of Sigmar/Tactics/Monstrous Arcanum

Forge World monsters of all kinds and sizes. Some of these are more or less part of another army, because they have the relevant keyword (Dread Saurian is a Seraphon, for example), but others are kinda their own thing. These creatures don't share a common keyword, so there's no incentive to play them together, unless you want to make a thematic Monster army or something.

WARNING: The Monstrous Arcanum has been rewritten for AOS2. Many of the descriptions below are outdated.

Order Warscrolls

Carmine Dragon: The dragon every guy dreams about. Very hardy at 14 wounds and 3+ armor, with Chaos Warrior-like save of 5+ against mortal wounds, also hella fast. It can unbind spells and heal itself while doing it, and everything within 6" of him gets -1 Bravery. To top it off, it also shoots blasts of pure Death magic, dealing D6 + target Bravery - D6 + Carmine Dragon's Bravery (10, just great). Oh, and you re-roll the dice against Death and Daemons things (the ones with Bravery 10), so it isn't useless against them. With the -1 to Bravery of close units and its Bravery 10, you can easily deal 4-5 mortal wounds for each shoot, just awesome. Use this dragon with bravery-reducing shenanigans. Sadly this thing costs so much, you won't be able to field it in an ally list and so you'll have take Order allegiance instead.

Seraphon

Dread Saurian: A super Seraphon (that is, an Order Daemon with Bravery 10, that can be summoned) with good speed and endurance, that regenerates some wounds after inflicting damage, vampire-style. And with multiple attacks at -3 Rend (that is NOT reduced after the Saurian takes damage), and 40k's Preferred Enemy against Monsters (re-roll 1's in both hit and wound), it'll indeed deal catastrophic amounts of said damage. But it's no mere scary monster, because it also makes every unit at 12" of it take Battleshock at -2 Bravery, making it a great team player indeed, and also very useful with Bravery based abilities and spells. One of the most solid and consistent Monsters of the game, I'll say.

Chaos Warscrolls

Chaos Siege Gargants:

Chaos War Mammoth:

Gigantic Chaos Spawn:

Preyton: Yes, it looks weird, but it's pretty useful. It's fast, you can set it up almost anywhere, and it's decent at combat (but also fragile). The great thing about it is that if it manages to wound something with its soothing attack, then that unit has -1 to hit until your next Hero Phase. Teleport it near some crucial enemy unit, shoot it and reduce the accuracy of its guys, then charge it with some other nearby unit to guarantee a nasty battle. Problem is that you have to set the Preyton up on your first movement phase, and that its shooting attack it's very weak, but it's still a pretty versatile and useful Monster.

Skin wolves: Warhammer werewolves, but they're not Death nor Beastmen units, but Chaos, remember it. They're fast and reasonably damaging, but quite fragile, so you'll have to part with them very soon. Their double leaping pile-in can be useful to attack Heroes hiding in a unit, or even avoid them and start killing the unit itself.

Warpfire Dragon: The weird cousin of the Carmine and Magma dragons, that tries to be useful but ends up causing disasters everywhere he goes. Yes, he can be pretty killy, and it's fast, but he's too random and fragile to trust him with anything but suicide/distraction attacks. If your opponent has some elite ultra-armoured big unit, he can make a good name for himself, though, because he spits mortal wounds by every orifice of his body.

Khorne

Exalted Greater Daemon of Khorne: here.

Mazarall the Butcher: here.

Skaarac the Bloodborn: here.

Nurgle

Exalted Greater Daemon of Nurgle: here.

Skaven

Brood Horror: A pretty lame at everything giant mutated rat. It's a Skaven Moulder, so you can buff it with some minis, but very unremarkable and ability-less overall.

Skaven warlord on Brood Horror: Not many people know this, but giant mutated rats become pretty good when crazy ratmen mounts them. In particular, the lame Brood Horror becomes very good, gaining +1 Save, extra attacks, and replacing the Moulder for the Verminus keyword. It also gives +1 Bravery to Verminus units within 13" (Bravery being, apart from randomness and killing each other, Skaven biggest problem), and it gains a great Command Ability, granting and extra attack for each melee weapon for a Verminus unit within 13". This pair is great in Verminus armies, and pretty useful in other Skaven armies (just don't make him your General then).

Skaven Wolf Rats: Light cavalry, more or less, for the Skaven Moulder faction. Incredibly vulnerable outside of combat, but pretty decent if they reach melee with their 10" Move. Good as distraction, but don't rely on them. By the way, they aren't a Monster, so who invited to this party?

Warpgnaw Verminlord:

Slaves To Darkness

Curs'd Ettin: Pretty fast, but badly armored, and not killy enough. A little lame, but it's a Mortal Chaos unit, so you can make it better with some Slaves of Darkness things. But you can't give him a Chaos Mark, so it'll never be truly useful, I fear.

Sayl the Faithless:

Nightmaw:

Slaanesh

Exalted Greater Daemon of Slaanesh: here

Tzeentch

Exalted Greater Daemon of Tzeentch:

Death Warscrolls

Nighthaunt

Mourngul: Broken. Like most Death units, they can be summoned, but do not ever do this, as playing a Mourngul is already a dick move, but summoning one will result in your opponent flipping the table. Why is the thing so dangerous? Well, like all the other Ethereal stuff, its Save is unaffected by Rend. Problem is, it has a 3+ and like the Bastiladon also a 4+ against Mortal Wounds. As if this was not enough, it has 10 Wounds and regenerates in every turn it killed stuff, which will happen. A lot. It only has one weapon profile, but that one is a doozy, with lots of high Rend, high damage attacks that have a chance to generate extra attacks (that have a chance to generate extra attacks). It also lowers the to-hit rolls of nearby units by one (awesome), or by two if they have 6 or less Bravery, so if you can lower their Bravery with something (a Screaming Skull Catapult, some banners, etc) it becomes almost immortal. In other words, most enemies cannot hurt it reliably and if they don't kill it fast enough, it'll charge them, eat their sorry asses and fully recover.

Destruction Warscrolls

Basilisk: Fast, fragile, and nothing to write home about in melee. But it has an awesome ranged attack, so keep him close to the enemy, but well protected, and it'll do wonders.

Dread Maw: Even if you hated giant desert serpents/worms before, you'll start loving them when you meet this guy. It has a Save of 3+, but also a save-after-the-save againts both wounds and mortal wounds of 4+. And that, my friends, it's the equivalent of a 2+ Save, the best natural save ANY unit in Age of Sigmar gets (though other creatures are arguably even more hardy). It's also pretty fast, ignores terrain when moving, and can teleport to within 6" of any table edge and more than 9" from the enemy. Oh, and its attacks do enormous amounts of damage (especially against horde units) with a lot of Rend ( -3 until it receives 4 or more damage, brutal indeed). It was associated with the Nehekhara deserts in Warhammer Fantasy, but now it's a Destruction Monster. But there's no army that can't benefit with an almost unkillable monster that pops out of nowhere and starts charging and destroying things like the scenery was not even there. Use it, love it.

Fimirach Noble: Ok. Just ok. Can technically dish out up to 13 wounds per combat but you would have to be really lucky. (5 attacks, 6's to wound add mortal wound, d3 damage club tail). His command ability is kinda phoned in too. Re-roll charges for units wholly within 12", not only doesn't do anything for the fluff of 'mists and terror'. Also its not very helpful if you're trying to take larger units of Fimir, as keeping them all within 12" gets clunky. Take the rockeye and might is right for plus 1 to hit and wound your preferred target and keep him close to the warriors who need the extra punch to finish off opponents.

Fimir Warriors: Everyone's favorite one-eyed mist abductors are here again. They are "Monstruous Infantry" with Ogor-like stats and some nifty abilities. In the Hero phase, they regenerate any Wounds they have taken, so if you manage to keep some of their 3 wounds after both your and your opponent's turns, they're basically invincible. But do remember that in Age of Sigmar you can't redistribute wounds between your guys, after you assign one wound to a model you have to keep doing it until it dies. Just cast Mystic Shield on them. Despite being the only Ogre-sized great weapon wielding unit that only manages one damage per hit they also do double damage on 6's to wound. and have some pretty good protection against shooting attacks. They're very good at screening your other units, or you can just protect and heal them to get an indestructible and very damaging unit. Not bad at all, let's hope this time they don't start raping people and get squatted again! Fimir Warrior will not devastate and break your opponent in one round of combat, but they can tie them up and really wear them down. Keep a Monster or Hero close to tip the scales in their favour

Incarnate Elemental of Beasts: A Destruction Daemon with decent Move and survivability, and lots of powerful CQC attacks. It has a pretty good shooting attack that deals mortal wounds, it gets the same "-2 to Bravery" aura of the Dread Saurian (but only 8" range), and regenerates a wound a turn if you're in the Realm of Beasts. Pretty useful overall, but perhaps not special enough. As always, use its Bravery-reducing ability to its fullest and it won't disappoint you.

Incarnate Elmental of Fire: A weird Monster, in the sense that it's great not in melee, but in ranged combat. It makes lots of pretty good shooting attacks, that at -1 Rend are the utter bane of hordes. Also a roll to wound of 6+ for ANY of its attacks deals double damage, and its fiery aura deals mortal wounds to nearby units. Like the Incarnate Elemental of Beasts, it's a Destruction Daemon and it regenerates a wound each turn while in the Realm of Fire. Somehow slow for a Monster, but good both at range (18" max) and at close combat (you can shoot into melee). All in all, very versatile and quite powerful.

Magma Dragon: Preeeesenting the king of Monsters, the Godzilla of Age of Sigmar, the nastiests non-named thing you can put on the table! It's like a Necrosphinx that, instead of decapitating Monsters, goes around incinerating hordes with a 18" shooting attack that, on a 2+, deals D6 mortal wounds to some poor bastard, or an incredible 2D6 if the unit has 10+ models. But like the sphinx you can just fly here and there killing any and all things with a supersonic 16" Move (at top form) and droves of obscenely powerful attacks. All at 20 wounds, like you were the Everchosen or something. This thing is for the guy who despises complicated plans and sissy synergies, and just wants to go for the throat with the biggest and baddest Monster around. Be aware, though, that it costs 480 points, so avoid things that can tarpit your Megazord for some turns, or disable it with some tricky spells or abilities, while the opponent takes care of the rest or your (quite possibly outnumbered) army. Still, with your power and speed, not many things can do that...

Merwyrm: Slow, well protected (-1 to Hit for ANY attack against it), and nasty agains other Monsters. Also regenerates when inflicting damage and ignores water and swamp-type scenery. Very good if you can heal/protect it, it'll be unkillable while still doing lots of damage. It's also very fluffy with a Dark Elves army, because their pirates used to hunt and use these things when there were no Stormcast Eternals around, and Dhorghar had size insecurities when looking at Deathclaw.

Greenskinz

Rogue Idol: Powerful and hardy, but quite slow and random. It still does provide very useful bonuses for Greenskinz and it's no slouch in combat, if it ever reaches the enemy lines instead of chasing a Gryph-Hound or something. Can be very good, but it requires some care and finesse. But you have these in spades, because you're an Orc, after all. Ahem.

Gloomspite Gitz

Colossal Squig: Random and not very durable, but fast and scary as hell. Keep it far from your other units, because it might eat them up; send it to the enemy lines asap. It's a Moonclan unit, so buff it and start the carnage.

Squig Gobba: Almost useless artillery-like unit. Can deal some damage turn after turn while being inaccessible to the enemy, thanks to its ability, but even with that it'll probably be useless. Avoid unless you love it or something. It's a Moonclan unit, remember that.

Troggoth Hag: Next time you need to subdue a raging boner, just remember the Troll Hag's hanging breasts and you'll lose it, guaranteed. And not only that, this lady is incredible in the tabletop too. She has an amazing shooting attack, amazing protection, amazing regeneration, and and amazing spell. Giving -1 to Hit AND Save rolls will turn an elite unit into a mediocre and weak-ass one, and it's effectively two spells in one by itself. And the Hag can even kill Wizards while unbinding their spells! Her only weakness is perhpas her slowness, so make the way clear for her and she'll be your sweetheart. Don't think of her as some random useful Monster, think of her as a centerpiece unit that can give you the game if you use her well.

Bonegrinder Giant: A king-sized Giant, with a powerful but inaccurate ranged attack, and good armor (4+). Quite fast and powerful overall. Otherwise a pretty vanilla Monster.

External links

All the warscrolls, all up to date and with current matched points are in a single pdf. That sort of useful and convenient efficiency is why Forgeworld models costs more. https://www.forgeworld.co.uk/resources/PDF/fw_warscrolls/aos-monstrous-arcanum.pdf

Age of Sigmar Tactics Articles
General Tactics	Tactics Realm Of Battle Malign Sorcery Path to Glory Skirmish
Order	Cities of Sigmar Daughters of Khaine Fyreslayers Idoneth Deepkin Kharadron Overlords Lumineth Realm-Lords Seraphon Stormcast Eternals Sylvaneth
Chaos	Beasts Of Chaos Blades of Khorne Disciples of Tzeentch Hedonites of Slaanesh Maggotkin of Nurgle Skaven Slaves to Darkness
Death	Flesh-Eater Courts Nighthaunt Ossiarch Bonereapers Soulblight Gravelords
Destruction	Gloomspite Gitz Ogor Mawtribes Orruk Warclans Sons of Behemat
Others	Monstrous Arcanum Legends Old Rules