Coming back to the game after over a year away. I don't know what new stuff is worth getting or how much to get. I was hoping to get suggestions on starting.
Build an army with your old stuff and play a few games. See what you are missing in your list and you can start adding new stuff. Nothing is so overly powerful that you must have it in your list.
Lambs and Lions has a good suggestion to play some games to get a sense of things. But if you're looking to get a quick sense of the new landscape for Seraphon after the new battletome, I'll try to give you a quick rundown. It's important to note that the new battletome's official release was just a few weeks ago, and the new models came out then as well. We are are still learning the new army, so take anything I say with a grain of salt. The troops are also a bit different depending on whether you are playing Starborne or Coalesced. Both factions have strong magic, but the Starborne magic is stronger and more offensive, with teleportation and very good summoning. Coalesced is tough and has new monstrous rampages for each Seraphon monster. Neither faction is extremely fast or extremely strong with shooting or melee, but the magic helps mitigate this with strong and flexible buffs and debuffs. Many of the units feel over-priced, points-wise, but the magic mitigates this. With magic and abilities, both armies are very mobile, and can do a lot of board control. Starborne leans toward many cheap screens and Coalesced has some decent anvils, but both factions can do either approach to a point. Also, we lost some units, including the Skink Priest (we have no priests now), Eternity Warden, Saurus Sunblood, Saurus Knights (but they were replaced) and Razordons. The Salamander was changed to the Spawn of Chotec and the chameleon skinks have become the Hunters of Huanchi, with different weapon options. Here's a quick rundown, starting with the units that are new: Raptadon Chargers - the new skink melee cavalry are very good, and are the most point efficient attackers in the army, especially on objectives. The are fragile glass cannons, but are cheap and fast. In Starborne, they can be summoned pretty easily, potentially 7" from an enemy, and get +1 to charge rolls, allowing them to steal objectives or deal significant damage. They are battleline in the Fangs of Sotek subfaction, where they also benefit from the free redeploy ability. They are cheap enough to use as wide oval-based screens. The base is the size of the Saurus Knights' base. Raptadon Hunters - the ranged skink cavalry are okay, but not amazing. They buff the Raptadon Chargers, and are buffed by them, but it's usually going to be better to just bring more chargers instead. The base is the size of the Saurus Knights' base. Aggradon Lancers - the new Saurus Cavalry are the fast hammers of the Seraphon. Unfortunately, they aren't that fast for cavalry, or as tough as a lot of other armies' cavalry, but with proper buffs, they can go very fast and be quite tough. People are just starting to get the hang of them, but I've been hearing good things. They are battleline if the general is a Saurus, which you can do in Coalesced but wouldn't usually want to in Starborne. In Coalesced they are also tougher and get +1 to would on charge in Koatl's Claw. They are less point efficient in Starborne, but still can serve a useful role there. The base is larger than the Saurus Knights' base. Saurus Scar-Veteran on Aggradon - this hero can buff the Aggradons once per game. He's is underwhelming on his own, but could be good in a heavy Aggradon list, or if you need a cheap general so you can allocate points elsewhere. This base is bigger than the other Aggradons' bases. Spawn of Chotec - the new Salamander is good for the cost. He no longer dishes out mortal wounds, but can still shred screens and chaff with his 12" ranged attack and decent melee profile. In Starborne, he's another good unit to teleport in to have him shoot and maybe charge. He also has an alternate 24" range attack that is unreliable, but if it does damage, the enemy unit gets -1 to save. This can be a useful threat on the board and occasionally debuffs an enemy. The base is larger than the old salamanders' bases. Hunters of Huanchi - the new chameleon skinks are similar to what they were, except now they can't be seen at all when they are more than 12" away or while they are in cover, so they can't be targeted for shooting or enemy spells. They can still go back into reserve to teleport over two turns. You can get them with dartpipes with venom that do mortal wounds, or with clubs and bolas. The later is cheap, and so great for nabbing objectives away from the battle. Lord Kroak - still very strong in both factions. His signature spell, Celestial Deliverance, was upgraded in several subtle ways. It can now be cast 4 times instead of 3, the casting value stays at 7, and the range went from 10" to 12". Kroak's base is much bigger than his old model's base. Slann Starmaster - still very good. It lost Comet's Call on the Warscroll, which is now part of the Slann spell lore for Starborne only, but it got some new Warscroll spells that are decent. This base is also much bigger now. Saurus Oldblood on Carnosaur - better than ever. It has rend now, and doesn't bracket so fast. As a general, command traits and artefacts can make it extremely deadly for its cost, or you can use those to enhance the army's mobility and objective control. It can issue two of the same command for one command point every single phase, which is amazing! Saurus Oldblood - he seems okay, but there's nothing phenomenal. Fairly cheap though. Saurus Astrolith Bearer - he hasn't changed much, but it's as essential as ever for the magic boosts. Saurus Scar-Veteran on Carnosaur. Everything about this is the same as the Oldblood on Carnosaur, except that instead of being able to issue two commands per phase, he has a damage ability that will, on average, do a third as much damage to an enemy hero or monster as it has previously taken at the end of the combat phase. So it's likely to kill any enemy that has only 25% of it's wounds left. Not bad. Skink Oracle on Troglodon - this hero is excellent now! It can still vassal cast for the Slann at any distance, but now it's much tougher and possible to buff defensively to the extreme. And it regenerates D3 wounds in both players' hero phases. It has a 9" -1 to hit aura around it, making it harder for your enemies to hit it or your units around it. Enemies can't use Inspiring Presence within 3" of it, and the Warscroll spell can make it very difficult for your enemies to move around and charge. It's powerful in both Starborne and Coalesced, but will likely be used differently in each. Skink Starseer - this model has become amazing, with two spells per turn, a great Warscroll spell and a great ability. It's very cheap for what it is. Skink Starpriest - still very good, because skink spells are good, but the Serpent Staff ability is not as amazing as it used to be. The ability hasn't changed, but our units just won't dish out the mortal wounds with it that they used to. Skinks - they are very good as cheap, mobile screens that can run and redeploy very well (they roll 2 dice and choose the best one). But they can't be buffed like they used to, so no more big hordes to deal crazy damage. Saurus Warriors - super good, especially on Coalesced. They are finally tanky, able to absorb a ton of damage. They have 2 wounds, get a 3+ save in their own territory or on objectives, and in Coalesced they absorb damage and get +1 to wound on charge in Koatl's Claw. They are also still decent in Starborne. They finally have rend. They get bonus bite attacks that deal mortal wounds, which are stronger in Coalesced. Great reinforced in units of 20. Saurus Guard - like Saurus Warriors, but they always have 3+ save, are a bit better in melee, but come in units of 5 instead of 10, so don't dish out as much damage because they can't be in as large a unit. They can now absorb wounds for all non-monster heroes, not just Slann, which is great for protecting skink wizards and the Astrolith Bearer. They get bonus bite attacks that deal mortal wounds, which are stronger in Coalesced. Kroxigor and Kroxigor Warspawned - two types of Krox with slightly different pros and cons. They are good in reinforced units where they can attack from the back rank for significant damage. They get bonuses around skinks. They get bonus bite attacks that deal mortal wounds, which are stronger in Coalesced. They are good, but probably a little over-priced. Bastiladon - The Solar Engine isn't as good as it was, but it's still good. With -3 rend, it can do damage to hard targets. It's probably overpriced, but it's still an important unit in the army. The Ark of Sotek is better than it was. It's pretty cost efficient, but serves a less critical role than the Solar Engine. We're not sure if this is an error, but the skink keyword was removed. Ripperdactyls - they're okay. They are cheap, fast flying units that can target ranged units and maybe do some damage without getting killed on the way in. Terradons - cheap and very fast. The fastest screens in the army. Stegadons - good, but not like they used to be. They can't be buffed up like crazy anymore. They count as 10 models for contesting objectives, which is good. They are overpriced. In Thunder Lizards, they are battleline and don't count as behemoths, so you can bring a lot of them. Engine of the Gods - nothing like it was and not great. It's not a priest anymore. It's basically a Stegadon that trades some abilities for a chance to heal every turn or cast an attack spell every other turn. It's other abilities aren't worth trying. Definitely overpriced.
With the updates to rules and points with the new General's Handbook, Battlescroll and FAQ, a lot has changed for us. I thought I would add some updates to this list. Aggradon Lancers - this may be the single most important chance in the list. They had a small point drop, but more importantly, the new coherency rule causes a major makeover of this unit and the Seraphon army. 6 models are now in coherency when within 1" of just one other model the unit. This means that a reinforced unit of Aggradon Lancers can stand side by side and get in all their attacks. This makes them a proper hammer, and the only hammer in our list that isn't a glass cannon. 6 Aggradon Lancers can be buffed together and cause some serious damage. In Coalesced, they are stronger (in Koatl's Claw) and more resilient, but in Starborne they benefit from the list's mobility and can drop in for a 7" charge at +1. They are now a key units for both factions of our army. Many lists will benefit from having one or two units of reinforced Aggradon Lancers. Saurus Scar-Veteran on Aggradon - now that the Aggradons are a solid hammer, the Scar-Vet on Aggradon is decent. His ability to give Aggradons +1 to rage (+1 attacks for the mount) once per game can be very impactful now on himself and one of two units of reinforced Aggradons. He also got cheaper, so will be worth putting in some Aggradon lists. Hunters of Huanchi - the new Look at Sir rule gives these guys a new role. If there are 3 models in a unit near a hero of less than 10 wounds, that hero can't be shot from more than 12". Normally, this could be dealt with by shooting and wiping out the protecting unit, and then shooting the hero, but the Hunters of Huanchi themselves can't be shot from more than 12". If they're in cover, they can't be shot at all. This makes them excellent protection for small heros that are hard for our enemies to deal with at range. Lord Kroak - his points went up and he took a series of small nerfs. He's still very very good, but with vassal casting limited to once per turn, he will need to get into the thick of the battle, where he is more vulnerable and can have his spells unbound, to be at his full potential. Without Cogs, he is likely to miscast about every other game, which can be devastating. And like Kroak, the Saurus Guard that protect him went up in price too. And as expected, the Coalesced spell Telepathic Summons was nerfed, so he loses a lot of that utility. The spell works on all non-monster Seraphon now, rather than only Saurus, which does open some new doors, including Kroak or a Starmaster casting it on themselves through a vassal to teleport themselves to that vassal. (You can also cast it on a vassal through that vassal to remove the vassal from play and not be able to set it up again, but don't do that). Slann Starmaster - the vassal cast nerf doesn't hurt the Starmaster that much, since his Warscroll spells and Comet's Call do not have range considerations. But it hurts him a little bit, as Mystic Shield, Endless Spells and his other Lore Spells are affected and he can't vassal cast two of those. Most turns he didn't need to, but it will come up often enough. But he's still very very good, with good spells; 3 casts; +1 to cast, unbind and dispel; board-wide unbind; generates command points; and can give a unit flying and -1 to be shot. But he's also hurt a bit by the Telepathic Summons nerf in Coalesced. Saurus Oldblood on Carnosaur - a nice point drop makes this great model even better. Skink Oracle on Troglodon - the Slann can each only vassal cast through him once a turn now, which is hurts him, but his cost didn't go down like most units. He's still very good, but less cost efficient, making it harder to justify him in some lists. However, the rules of his Primordial Mire spell have been clarified, and it's a truly powerful spell that can stop enemies in their tracks. Effected enemy units will have trouble charging your units; especially if you redeploy after they move into charge position. With charge rolls halved, a 6" charge is as hard as a normal 12" charge for affected enemies. Saurus Warriors - this great unit got a price cut! And their bite ability has been improved so that they deal damage before enemy models are removed, meaning the opponent cannot remove models that were killed by club or spear to get their unit out of bite range anymore. Kroxigor - like Aggradons, reinforced Kroxigor benefit from the new coherency rules. They could already hit with their weapons from the back rank, but now they can get all their 18 bites in. This is helped by the rule change that their bites happen before enemy models are removed from play, too. Bastiladon with Solar Engine - he takes a small nerf since he won't be able to target small heros from more than 12" away. He can still dish out damage to monsters and large heroes, but to snipe those key buff units, he'll have to get in close. Fortunately, he's tough enough to do that, and can be teleported in Starborne. His cost dropped a fair amount, which helps soften the blow. Ripperdactyl Riders - another beneficiary of the new coherency rule. Reinforced Ripperdactyls are very good now. They are comparable to flying Raptadon Chargers, doing similar damage output, but being optional against key units with blot toads instead of objectives. This is great, as the new Look Out Sir rule makes it hard to snipe small heros with shooting, but we can now feed them to the Ripperdactyls. Ripperdactyls are much harder to shoot than Raptadons, especially with Unleash Hell. They can be teleported in with Starborne for that 7" charge. And they are cheap to summon, so if you start with one or two units of Ripperdactyls, the summoned ones will benefit from the blot toads, too. Ripperdactyl Chief - like the Scar-Veteran on Aggradon with the Aggradon Lancers, the Ripperdactyl Chief can boost Ripperdactyls once a game, which can be decent now if you bring one or two units of reinforced Ripperdactyls. And he comes with another Blot Toad that any Ripperdactyl can benefit from. Oh, and give a Starborne Ripperdactyl Chief (or Terradon Chief or Stegadon Chief) an Arcane Tomb and he not only becomes a Cosmic Node and generates CPP, but if also a new skink vassal for the Slann to cast through. Stegadon - these guys got the needed 40 point drop, making them a stellar unit. They are now worthy of being in any list, and can be brought as non-behemoth battleline in significant numbers in Thunder Lizards. Engine of the Gods - sadly, nothing changed with this unit. It's price didn't go down like most of the army. It is now considerably more expensive than a regular Stegadon and considerably worse. It was already the worst Warscroll in our Battletome (except maybe the Starblood Stalkers), and by not getting adjusted, it is even more garbage than before. A shame. While we did take some nerfs, overall I believe the changes and net cost reductions will benefit us. I think the army has more potential than before, as it was often difficult at the previous point costs to round out the list, and we didn't have reliable hammers. The new spell meta with the generals handbook is something we can still dominate, as we have great casting, though it would be to our advantage to try to get more Primal Magic Dice than our opponents so they can't counter our magic as easily. I'm excited to try all the new possibilities.
How do you find all this stuff? I'm so confused. I'm pretty new to AOS still and I would expect all this to be in one of two places. Either the General's Handbook (which I have a physical copy of and don't see this stuff). Or on the erratas pages for Seraphon. https://www.warhammer-community.com/warhammer-age-of-sigmar-downloads/#additional-rules Don't see any of this there as well. Can you help me know where to get the latest information on our army? Hopefully it's not spread across 12 books and links.
Most of this info should be in the Seraphon Battletome. Some of the info, like units of 6 having better cohesion rules and minor rule changes should be in the errata for Seraphon and/or AoS. Point costs can be easily seen on the Army Builder or the AoS app. You're welcome to ask any question about Seraphon or AoS and hopefully someone should come by with the answer.