Day 1 takes:
Siren Song is broken. Like potentially 8 mana Champions' Strength broken. There's like 5 different decks currently with it that have a 57+ win rate right now, and they're all entirely new decks. There's stuff like Eve Xolaani which can legit evolve Xolaani on curve. There's an Aatrox BW brew which also has Xolaani as a finisher. Old standbys like Eve Viego are obviously better. And there's other stuff like Eve Lucian. Genuinely wouldn't be surprised if it gets hot fixed, it's actually insane. It's 4 mana Spirits Unleashed that you don't have to play Freljord to get access to.
Poros are like the only deck trying to use Siren Call that isn't insane. Only ones with a positive win rate are Eve Poros, Champions' Strength Poros, and Xolaani Poros which has a rep in Masters right now. But those strategies are just better with other shells to be put into. It's a low interaction proactive deck that wants to start out-valuing the opponent on turns 5-7 in a format where people are playing Kai'Sa and Second Skinning Valor, resolving Champions' Strength, and playing 16/16s that instantly win the game on attack on turns 5-7. Most decks can either go underneath it or do something busted that can kill through some cheap infinite 4/4s or whatever the Poros are doing. I would be surprised if any Poro deck plays a role in the meta past the first couple weeks of the expansion unless there's a balance patch that substantially lowers the power of the format while buffing Poros.
Neeko Demacia seems actually good. It's yet another Champions' Strength deck, but it's like BC Demacia where there's a couple cards that give another card on play so you can keep restocking your board, and leveled Neeko is at worst a 4/4 Elusive that plays Spirits Unleashed every attack. I think there's probably a build with her that will stick around in the meta.
Nidalee there's some decks like Nidalee Ekko or a Norra Nidalee deck that are doing alright, but Ambush feels like too honest of an archetype in a format where the main control deck pretty much instantly wins when they untap with 10 mana, and there's a bunch of decks where if you don't disrupt their gameplan they can reliably do something so broken that you pretty much auto-lose on turns 5-7. I feel like the past couple patches Riot's been too soft on nerfs and as a result I feel like the amount of degenerate stuff in Standard is higher that it probably should be.
Lastly Xolaani is legit the best Targon champ in the game right now lol. At one point the Eve Xolaani deck played Kayle, but at this point I think people have figured out that at best Kayle is a Xolaani support card and doesn't really do enough for 5 mana in many decks because you actually have to attack with your boosted units to get paid off whereas Xolaani just needs them to die. So now there's a list popping up that leans harder into Eve and just drops Kayle altogether.
