Manaflow Band post patch 8.7
It seemed like an interesting rework, but the nerf is simply too massive. As a Brand support main, I used to be able to get about ~1700 mana refunded in a 30-40 minute game, but after the nerf I was only able to conjure 297 mana (+250 bonus mana given). I know these are just two games and not nearly a large enough sample size, but a ~66% nerf is huge, especially for early laning phase for any support that uses a lot of mana.
Presence of mind helps negate this post laning phase, but that initial laning phase mana loss means lane bullies are forced to do a lot less lane bullying.