I never played in tournaments, and have only sort-of kept up to speed. The L5R fora on their website might be a better place to ask. But
Current clans are: Crab, Crane, Dragon, Lion, Mantis, Phoenix, Scorpion, Unicorn, Spider, Shadowlands. Naga, Monks, Ratling: all dropped as supported factions.
The Spider clan is, basically, Shadowlands humans passing themselves off as a new clan in the Empire. Sort of a hybrid Shadowlands deck that follows the honor rules.
Rules have changed quite a bit. Dueling, in particular (and I used to play Crane) – double chi is gone, you focus from a focus pool you draw from your deck when the duel starts, the Duelist trait improves your focus pool – you’re better off reading up in a rulebook, really.
Card templating has changed (more intuitive, really). Other changes – such as no more “Fu Rule” – are rather minor, but there seem to be a lot of 'em. I think you’d be better off approaching it as though you hadn’t played before, by going to a L5R demo or playing with a current player first.
Allowed cards in tournaments are determined by the “bug” – at the bottom of the card, there’ll be a button with a kanji in it that indicates what playset it belongs to. There was “jade”, “gold”, now it may be “samurai.” If the tournament is “samurai” then your deck may only have cards with the samurai bug on it.
Some personality cards have the “Soul of” trait. If the personality has the appropriate playset bug, you may sub in the previous “soul” even though it doesn’t have the appropriate bug. They’re in the middle of a storyset, now, though so I doubt there’ll be much use for that, though. Better to just buy new starter packs.
Starter packs, by the way, are now sorted into “fixed” and “random” portions. The fixed portion is enough to give you a deck for that faction that is playable out of the box. You might get one or two unusables in the random portion, but for casual play they’re good enough to hand out to newbies so they can jump right in.
The storyline I’m not even going to attempt to explain. It’s a hot mess. After the Hidden Emperor period (during the Burning Sands storyline) there was the confusing Wizards of the Coast era in the “Spirit Wars” that jumped the timeline forward a generation. Then Toturi was killed, his four children “fought” for the throne – the “Four Winds” era – followed by more and more improbable whackiness and Mary Sueish characters. The current story team seems to be moving it to more “samurai drama”, though.
The artwork, however, is mostly fantastic. Some of it is exceptionally fantastic (e.g., shadow dragon, doji seo, Hoshi Masote – although those are a bit old by now).
