Mustrum_Ridcully said:
Compare a Fighter20 and a Barbarian 20 to a Barbarian10/Fighter10. They probably have the same combat ability.
Now compare a Wizard10/Cleric10 to a Wizard20 and a Cleric20.
They probably don`t have the same combat ability.
While this is true, the fighter-barb also does not gain much of anything in terms of broadening his range of abilities over the barb or the fighter. All of his abilities remain focuses in a relatively narrow band, which is precisely why they also stack together well to produce power.
In other word, the fighter-barb is almost as TALL as the fighter or the barb but also almost as narrow.
The cleric-wiz has, by comparison to either a cleric or a wiz a huge increase in width, gaining lots of new abilities by gaining spells of both major spellcasting types. The addition of domains, the various melee stuff also helps the wiz side a lot.
So while the cleric-wiz is not as tall as the cleric or the wiz by a long shot, he is much much wider than either one.
There is a direct linkage between overlap of the class abilities and gain in power... the more thay overlap, the more power but the less gain in flexibility.
Why does a Wiz10/Clr10 have to be on par in spell casting ability to a Wiz20 or a Clr20?
He doesn't.
What he needs to be able to do is to play on par with other characters of the same total level. With spell level being an element in some many things, including saves and basic spell power, the current reduction in spell power for anything close to the baseline 1-1 multiclass is seeming too steep at the higher level. Throwing a 10d6 attack with a save that is 3-4 DCs down does not compare as anything but a waste of time against a foe who can reasonable handle a 18d6 attack with a much higher dc.
I think, personally, the happy medium would be for a cleric-10/wiz-10 to have spellcasting ability in each class that approximates that of 15th level casters... though i have not spent the time to devise the mehcanics to make this happen. 2 spell levels down seems a good trade off in terms of loss of height for gain in width.
It could be as simple as adding a few feats for MYSTIC SYNERGY which allow a character with multiple spellcasting classes to raise his spell DCs and caster levels.
****************
MYSTIC SYNERGY
PRE: Must have two or more different spellcasting classes
Effect: The caster level and save DC for all spells for ONE of his classes are raised by 1 for every three levels in the other spell casting class (round down.) So for example, a cleric-9/wizard-11 who took this feat for his cleric class would cast any cleric spells at 12th level as opposed to 9th for all caster level purposes and with a bonus to save DCs of +3.
Special: This feat may be taken once for each class, so a cleric-wizard could take it twice, once for wizard and once for cleric.
*******************