Alright, so. Black Mage

All that MP fanangling is unneeded with just the "Independent UI tick".

UI/AF 3 do not reduce the GCD, only the cast time. The .625 Second deadzone between phase transitions would mean there's no risk of an MP deadzone.

Making the ice spells better at the expense of making F4 worse is horrible. We minimize Ice spells heavily. We only ever cast the one in UI: B4. Increasing B3's potency is an empty gesture beyond the very first cast. You have listed no changes regarding the damage reduction of Fire and Ice.

In the case that it is removed: We aren't suddenly going to use ice spells. There is no difference in time or cost between the two in spell tiers. Given the choice, we want to cast fire. Fire's bonus would have to be completely removed or reduced to the point of nullification to make it something to consider. Ice and Fire have the same exact cost regarding mobility, so given the choice you never choose Ice.

In the case that it stays: ^^^^^^^ Double down.

I will never use Scathe, stop trying to make me!

Phase lengths look exactly the same. 7 GCDs + FS in fire, 6-9 seconds in Ice.

Black mage turret is reduced for no concrete gain.

The UI tick does, however, make Spellspeed a 100% damage gain compared to now though, where it doesn't influence your UI phase at all. It is possible the UI tick will reduce Ice phase further which means more Fire uptime.