Multiclassing Save Progression (3.5e Variant Rule)

Multiclassing Mixed Save Progression
This variant rule aims to simplify save progressions when multiclassing, preventing the overly high and substandardly low saves that may result normally. Characters calculate their base save bonuses by their total HD rather than by the HD for each class separately.
 * If all the character's HD have the "Good" progression for the save, leveling up continues as normal, regardless of classes taken.
 * If all the character's HD have the "Poor" progression for the save, leveling up continues as normal, regardless of classes taken.
 * If the character has some "Good" and some "Poor" progressions for a save in his various HD, he uses the "Mixed" progression for that save, adjusting accordingly.
 * Upon multiclassing, a character's base saves might jump up or down depending on his new progressions.

Example: A rogue 1, bard 1, minotaur (monstrous humanoid 6) has 8 HD. Each of his HD grants a poor Fortitude save, giving him a +2 base save. Each of his HD grants a good Reflex save, giving him a +6 base save. His Will saves are split between one poor for his rogue level and two good progressions for bard and monstrous humanoid, giving him the mixed progression and a +4 base save. Under standard multiclassing with saves, he'd have +0 Fort, +9 Reflex and +7 Will.