I started a game in 296. CE in Pannónia.
I use the modified system from Sub Rosa 16. Chapter Britannia. For Character Generation we use Option I.
My question is what to use instead of Magic Theory to calculate Vis handle limit and other modifiers for Lab Total?
I try to run with different Form Lore-s, but I feel it is very restrictive to use all the different Form Lores, bc PCs need too much XP to advance in different Form Lores to handle different kind of Vis.
On the other hand I don't want to go with Accelerated Ability - Form Lore, bc that could lead to insanely high Lore in a specific Form, and one PC is a proto-Verditius, so he could end in double or triple boni based on accelerated Lore ability.
If a Gifted character comes from a good Magical Family, you might make their and the SG's life a little easier by giving out a standard Ability Muddle Through of level 0 or 1, not raisable by any means, and using that to replace Magic Theory in rules where a character has no pertinent (Form) Lore. That makes more ArM5 rules available to the characters.
Other approaches to pre-Bonisagus sagas could use Hedge Magic traditions or some Ancient Magic instead.