Issues

Too slow. Resolving a combat that includes 4-6 mages all casting preparatory spells beforehand and also spells in a combat is going to take you hours to work through the rules. The core book does include "Down and Dirty Spellcasting" mechanics but I find them too simple. I want something in between, that keeps the game moving a little faster (5 minutes of prep for a combat and no more than 1 minute per spell cast inside of combat?) while not losing the sense of depth of casting complex wizard spells with rules and dice.

There is a table of Yantras to choose from. Choosing them can slow down the game when you're all mages and you want to be casting spells frequently. (In the core mechanics, this is not a problem in combat, as extra yantras add cast time, so players usually only use 1 yantra.)

Spell factors like Duration and Scale have tables too. By spending Reach you can switch the tables to a different set of tables. It's a lot of tables! Can we reduce the need to look things up or use a special helper application or spreadsheet? Can we achieve flexible spell casting rules you can do in your head from memory? Let's aspire to it. Even if we don't achieve it we will still have a simpler rule set and lighter mental load both in and out of play.

Subtracting dice is confusing. You can boost a spell's Potency by 1 for each 2 dice you subtract from your dice pool, making your spell less likely to succeed (or succeed exceptionally!) in exchange for making it stronger. You can do something similar with other spell factors like Scale. It's is a difficult mechanic for new players to get their heads around. Players often do not know how much to subtract and still have a reasonable chance of success. It feels wrong that you increase a spell's power bit by bit but as you do, it has a chance to fizzle completely and do nothing. Even if this is an interesting risk/reward mechanic, thematically it does not make sense to me.

High Speech is a cargo cult. Players often resort to High Speech instead of other yantras, as the quick default choice. This reduces the uniqueness of each mage. Let's encourage unique spell casting yantras instead. I want to learn more about characters as they practice magic. Also, I suspect deferring to High Speech is an indication that choosing Yantras is often considered onerous.

Mana tracking, is it fun? Is ammo tracking for an archer in D&D fun? Is a Mage that is out of mana fun to play? Ultimately we want to keep it, because it's so deeply thematic. Can we make it less frequent, to minimise accounting? Can we make it less arbitrary like an annoying cost you must pay just to do the thing you wanted to do? Can we tie it to the role playing more? Can we use it as a pacing mechanic? (Lots of Mana makes players feel safe and buffered from harm. Empty Mana makes players feel stressed and makes them take risks.)

Tracking active spells and conditions. It seems hard as an ST to keep track of 5 mages with 2+ active spells each. Can we make their job easier? The game has Conditions which you can write on a character sheet or print out cards to hand to a player so they can keep it with their character sheet to remember that they have a condition, but every spell can have a Duration spanning many real world hours and no special cards to track them. Can we unify or simplify all this status tracking work somehow?