herald is worth getting if the opportunity cost is low. say your top laner shoved wave to their second turret, and your mid is present with their mid and your bot is just doing whatever with their bot then you can take herald easy no problem and shove in mid.
shiv is good for extra waveclear and works good in conjunction with firecannon since they both apply energised attacks which count as separate procs, so your next attack will proc both effects for a massive spike. and since at that point you would probably have 80% or 100% crit, you'll get a shiv crit too. firecannon is super nice on its own if you want to poke too, like in siege situations where you can chunk someone hard before pushing the tower down which might force them out the fight.
pd is a solid dueling item thanks to the damage reduction from your last target and being able to move through minions, but shiv+firecannon is normally better. runaan's isn't so hot right now because the bolts don't just fire to adjacent enemies, the adjacent targets have to be in your auto range which makes it a lot weaker right now so it's not really worth building in most cases.
death's dance seems quite weak for what it does, you either want to be avoiding burst with positioning or actually having a defense against it like a veil, qss or even sterak's. scimitar gives lifesteal too, which death's dance kind of does too but has an actually useful active.
the game is snowbally because turrets are made out of paper and teleport was nerfed which is making ignite super popular again which makes it very easy to snowball your lane, shove your tower, shove in other towers and just create insane pressure around the map. your adc can't just lose lane anymore and freeze for the next 10 minutes and hope for scaling to kick in because by then your top lane inhibitor will be down and they'll be banging on the door of your mid inhibitor turret. since your team won't be able to win the 4v5. this makes playing champions according to lane match ups infinitely more important and makes early junglers crucial since they can take the game far enough out of the grasp of the other team that their falling off won't even matter when you're up against two lanes of siege minions with baron buff at 22 minutes since they can just dance around your nexus turrets and take them anyway.