While champion nerfs and buffs impact the game tremendously, items do as well. Even more so, as they are far more applicable, and such is the case in patch 12.12 as well.
League of Legends patch 12.12 doesn't have as many item changes as we are used to from some patches. However, even these ones are bound to make some waves on the Summoners' Rift.
Riot state that they are adding some ability haste into Night Harvester's build path to match its buff last patch. With this, night Harvester now has a new build path of Hextech Alternator + Amplifying Tome + Fiendish Codex + 815 gold to full item. The change is not great, but every bit helps.
When it comes to Serpent's Fang, though, Riot are nerfing the item saying that Serpent's Fang was reducing shields by a lot more than intended thanks to a bug. Due to this, Serpent's Fang no longer applies additional shield reduction beyond 50% based on the enemy's bonus heal and shield power.
And, last, but not the least, is Shadowflame. Riot say that Shadowflame was underperforming due to a different bug that mitigated its damage based on the very magic resistance it was supposed to ignore.
And, just like Serpent's Fang, but only inverted, now Shadowflame's additional magic damage based on ignored MR is no longer mitigated by target's MR, thus making the meta have even more durability.