Chalice needs to get good or get gone
150% mana regen was a GREAT idea...but now we can address the elephant in the room: 
It sucks. Horribly. No one likes this shit. No one liked it before FQC was even a thing, assuming they knew what they were doing with their mana. Even if a mid laner wanted regen, they get Morello's...well...after FQC gets nerfed. Supports sometimes get noob trapped by it by building FQC + Athene's...like how on Earth is this not the stupidest idea ever? Crucible uses it, but I think a better idea would be to make 2 new items with the cleanse effect that either gives some tank stats or some ap, rather than using Chalice. That would encourage nearly any support to build that cleansing effect when needed because it'd be more efficient to do so, even if they're mage supports.
Main point is that Chalice and Mana Font in and of themselves are simply null and void when 150% mana regen is a way better stat to use to define what should be a premiere mana regen item. Should definitely rework the item or just replace it.
is almost completely better than
is underwhelming and
is mostly bought for those that want its active and does not give all that good of stats for how much it costs.