The vast majority of Seraphine's player base is in support, where she's currently critically weak. Typically, we'd just buff her, but she's also significantly overpowered as a bot lane AP carry, which means simpler tactics aren't available. So we're trying again to close the gap between these two roles while being mindful of what players find fun about her in each play style.
For APC Seraphine, we're playing up her repeated damage. Q's missile speed and execute damage against champions has gone up and E is now worthy of maxing over W with a better AP ratio to boot. As compensation, she's losing a lot of power against minions and a bit of top-end ultimate power.
For support Seraphine, we're embracing her various builds. There's a logical case for every conceivable skill order and we're trying to make those choices viable based upon what game you're facing: Want to be primarily about shielding? It should be equally viable to max Q or E instead. Want to cosplay as a full mage and just deal as much damage as possible? Go right ahead, we think that option should also be supported.
We're also delivering some small support-skewed changes like shifting her mana toward regeneration, which synergizes with the support item, plus some base move speed, which is more important to a more roam-centric role.