The third way to modify the six stripped-down classes I previously presented is mixing -- combining two scaled powers. Base powers cannot be mixed; a character has either the Trickster's special surprise ability or the Charmer's special reaction reroll ability, but not both at the same time. However, the Trickster's subterfuge/cleverness bonus and the Charmer's reaction bonus can be combined; a Mixed Trickster/Charmer gets a subterfuge bonus equal to half HD (round up) and a reaction bonus equal to half HD (round down,) which means the character begins as a Trickster, then alternately increases Charmer and Trickster bonuses. Reversing the order (Mixed Charmer/Trickster) changes the starting class to Charmer.
Note that the maximum bonus for either mixed class is +5/+4, compared to a pure class's +9. Likewise, a Mixed Gifted/Magic-User would have a maximum power level of 3 for each.
Mixed classes, unless otherwise noted, use the base power of the first listed class. Hybrid Mixed Classes are possible, and are named thus: Hybrid X/Mixed Y/Z. You can also mix two variants of the same class: Mixed Magic-User (magic/illusionist). A Hybrid Fighter/Mixed MU/Cleric (druidic) with a wilderness-related background would be a reasonable substitute for the traditional Ranger class; Hybrid Trickster/Mixed Charmer/Cleric (druidic) with a musical background is one possible Bard replacement.
Experience and Hit Dice work the same as for a cross-type hybrid class: if one of the classes involved is supernatural, use the supernatural experience and HD progression (four times normal experience, 6 HD cap.)