Hello, Lustrians! I'm interested in returning to WH after leaving in 7th edition -yep, that's quite a bit of time. I have great expectations!
I'd be inclined to answer that thread title with "General Kenobi!", but I won't. Welcome to the forums!
AoS! Fantasy is a fond memory, but it has not the support that AoS has. I prefer to go with it. Are the GHB19 + FAQs/errata + battlescrolls from the web enough to have all the relevant, up-to-date rules? I'm a little bit lost with all the different places with information.
It is perfectly possible to have a game with Seraphon just using the Warscrolls and Core Rules on the free App (probably the best way to get hold of them given it’s updated pretty regularly). However, if you want to play competitively with them you will probably need a few other things as well. The GHB will give you Points values and Allegiance Abilities - if it’s just the points you want they can be found on the online Warscroll builder on the Community website but if you want the abilities too you’ll need the Handbook - they constitute quite a key part of tactics a lot of the time so it is quite important. If you’re going off the Warscrolls on the website you’ll need to check the FAQ for changes, but I’m pretty sure the app ones are up to date so if that’s what you’re using you’ll only really need it to clear up ambiguities using the Designer’s Commentary. Finally, if you do want to play at any level beyond casual, you are likely to want the Battletome. It has all the Warscroll Battalions, which also play a key part in most Seraphon tactics and lists, and while the Warscrolls are out of date it also contains some nice fluff and Battleplans which are great if you want to get into the army. If Seraphon is going to be a focus of yours it’s probably a good bet. As a general rule of thumb with AoS, you can get away with just playing with the Warscrolls and core rules, but if you want to play properly you will likely want the GHB2019 and if it exists, the Battletome for the army. Hope that helps
Welcome to the forums! I too joined the forums after a long absence. I started in 6th edition, quit, then resumed in 8th edition. Let us know if you have any specfiic questions about gameplay, painting, fluff or anything else.