How exactly does this work with more classes?
Ftr2/Wiz2:
Okay, so half the fighter levels count as Wiz levels towards Wiz casting progression. And half Wiz levels count as Ftr levels toward Ftr feat (or whatever) progression. So you're essentially Ftr3/Wiz3. Fine.
But now you add two Clr levels: Ftr2/Wiz2/Clr2:
Now are you a virtual-Ftr4/Wiz4/Clr4?
Keep adding more classes:
Ftr2/Wiz2/Clr2/Rog2/Sorc2/Druid2 becomes Ftr7/Wiz7/Clr7/Rog7/Sorc7/Druid7.
Leaving game balance out of it, it becomes a ridiculous headache to keep track of what levels add how many virtual levels to which ability progressions in which classes, for a total of what.
Good questions. I wonder how the ToB handles that?
Now, all this will assume that each class has real abilities that are both class specific, plus they're actually level appropriate for when they're gained. Something like the way ToB handles it with better and better maneuvers.
A few definitions before I get rolling. This is to help define what I'm talking about. Overall, it works basically just like ToB, but we need names for each class-specific combat option.
Maneuver = Fighter specific tricks, only gained through taking an actual Fighter level. These have an Initiator Level (like caster level in 3.X).
Spell = Arcane Spell, only gained through taking an actual Wizard level. These have a Caster Level (like caster level in 3.X).
Prayer = Divine Spell, only gained through taking an actual Cleric level. These have a Piety Level (like caster level in 3.X).
Trick = Rogue specific tricks, only gained through taking an actual Rogue level. These have a Trickery level (like caster level in 3.X).
Charm = Sorcerer specific tricks, only gained through taking an actual Sorcerer level. These have an Influence level (like caster level in 3.X).
So, the routine becomes this...
Level 1
Fighter 1 - Initiator Level 1, Maneuver Level 1 (appropriate for 1st level play)
Level 2
Fighter 2 - Initiator Level 2, Maneuver Level 1 (appropriate for 2nd level play)
Level 3
Wizard 1 - Caster Level 2, Spell Level 1 (appropriate for 2nd level play); Initiator Level 2, Maneuver Level 1 (appropriate for 2nd level play); Also, at this stage, he doesn't gain any new Maneuvers, since he didn't actually take a level of Fighter.
Level 4
Wizard 2 - Caster Level 3, Spell Level 2 (appropriate for 3rd level play); Initiator Level 3, Maneuver Level 1 (appropriate for 2nd level play); Again, no new maneuvers since he didn't take a level of Fighter.
Level 5
Cleric 1 - Piety Level 3, Prayer Level 2 (appropriate for 3rd level play); Caster Level 3, Spell Level 2 (appropriate for 3rd level play); Initiator Level 3, Maneuver Level 1 (appropriate for 2nd level play); No new maneuvers since he didn't take a level of Fighter. No new Spells, since he didn't take a level of Wizard.
Level 6
Cleric 2 - Piety Level 4, Prayer Level 2 (appropriate for 4th level play); Caster Level 4, Spell Level 2 (appropriate for 3rd level play); Initiator Level 4, Maneuver Level 1 (appropriate for 2nd level play); No new maneuvers since he didn't take a level of Fighter. No new Spells, since he didn't take a level of Wizard.
Time for a pause.
At level 6, he now has # of divine spell known as a 2nd level cleric, with a highest spell level of 2, and casts them at CL 4. He has # of arcane spells known as a 2nd level wizard, with a highest spell level of 2, and casts them at CL 4. (Oh, and his BAB is ****.
Level 7
Rogue 1 - Trickery Level 4, Trick level 2 (appropriate for 4th level play); Piety Level 4, Prayer Level 2 (appropriate for 4th level play); Caster Level 4, Spell Level 2 (appropriate for 3rd level play); Initiator Level 4, Maneuver Level 1 (appropriate for 2nd level play); No new maneuvers since he didn't take a level of Fighter. No new Spells, since he didn't take a level of Wizard. No new Prayers, since he didn't take a level of Cleric.
Level 8
Rogue 2 - Trickery Level 5, Trick level 3 (appropriate for 5th level play); Piety Level 5, Prayer Level 2 (appropriate for 4th level play); Caster Level 5, Spell Level 2 (appropriate for 3rd level play); Initiator Level 5, Maneuver Level 1 (appropriate for 2nd level play); No new maneuvers since he didn't take a level of Fighter. No new Spells, since he didn't take a level of Wizard. No new Prayers, since he didn't take a level of Cleric.
Level 9
Sorcerer 1 - Influence Level 5, Charm level 3 (appropriate for 5th level play); Trickery Level 5, Trick level 3 (appropriate for 5th level play); Piety Level 5, Prayer Level 2 (appropriate for 4th level play); Caster Level 5, Spell Level 2 (appropriate for 3rd level play); Initiator Level 5, Maneuver Level 1 (appropriate for 2nd level play); No new maneuvers since he didn't take a level of Fighter. No new Spells, since he didn't take a level of Wizard. No new Prayers, since he didn't take a level of Cleric.
Level 10
Sorcerer 2 - Influence Level 6, Charm level 3 (appropriate for 6th level play); Trickery Level 6, Trick level 3 (appropriate for 5th level play); Piety Level 6, Prayer Level 2 (appropriate for 4th level play); Caster Level 6, Spell Level 2 (appropriate for 3rd level play); Initiator Level 6, Maneuver Level 1 (appropriate for 2nd level play); No new maneuvers since he didn't take a level of Fighter. No new Spells, since he didn't take a level of Wizard. No new Prayers, since he didn't take a level of Cleric. No new tricks, since he didn't take a level of Rogue.
Second pause.
Fighter - He has a couple 1st level maneuvers, though his initiator level is boosted to 6th. He only has the initial crop chosen, plus what was gained at 2nd level, so very few of them.
Wizard - He has a couple 1st level spells, and a couple 2nd level spells, though his caster level is boosted to 6th. He has very few of those low level spells.
Cleric - Like wizard, except he gets to have 2nd level spells at CL 6, and very few of them.
Rogue - 3rd level tricks (as for 5th level play), and very few of them.
Sorcerer - 3rd level spells at CL 6th, and very few of them.
If you want, I'll keep going. All the way through 20 levels if necessary. Right now this is starting to look a lot less alarming with a longer explanation, and applying the ToB concept across the board.
