It didn’t take Seraphine more than a couple of days on the Public Beta Environment (PBE) before Riot realized that she was too strong and needed to be nerfed.
The nerfs are mainly targeting Seraphine’s damage, but are also toning down her general utility. Three of her abilities have received a nerf to their AP ratios, indicating that her numbers were a bit too high initially.
Q - High Note
First of all, Seraphine's High Note will take a pretty big in to its AP ratio. High Note is Seraphine's main damage ability, so this nerf will without a doubt impact her ability to play in the mid lane or in other carry roles. With a nerf like this, it seems that Riot wants her in a more supportive position, and nerfing her damage is one way to accomplish that.
W - Surround Sound
Riot continues its trend of nerfing Seraphine’s ratios by toning down the shielding, self move speed, and health restoration of her Surround Sound. This won’t affect her damage, but instead her utility, which means that her strength as a support will also be toned down.
E - Beat Drop
Lastly, Seraphine’s other damage ability Beat Drop takes an even bigger hit than her High Note on its AP scaling. Cutting down the AP ratio by 10% is a big hit for any ability, and will make her burst damage way less scary to opponents.
These damage nerfs might throw Seraphine completely out of the mid lane and make her a pick for the support position exclusively, but there is still room for testing. It seems that her power as a mage was too high and that Riot wants to balance her towards being a mage support champion.
The final state of Seraphine is still unknown as she continues to be tested on the PBE. It’s likely that more adjustments will be made to her before she hits the live servers.