Woohoo! Really fun find here (excuse me if this is well-known):
8th level Kensai can transfer part of their BAB or base save bonuses to a willing recipient using the Instill (Ex) ability. Here's the text:
Instill (Ex): Once per day, a kensai of 8th level or higher may take a full-round action to make a Concentration check (DC 10 + target's HD or character level) to impart some of his own ability into a willing ally he can touch. The kensai then transfers some of his power to the ally: He subtracts up to 1 point per class level from his base attack bonus and/or any or all of his base save bonuses and transfers the same amount to the recipient. The kensai regains the instilled power 1 hour later, when it transfers back out of the ally. If the ally dies before the instilled power is transferred back, the kensai must make a Fortitude save (DC 5 + target's HD or character level) or die as well. If he succeeds, he immediately gets his instilled powers back.
Note that the transferred BAB or base save points remain for an hour. Further note that there's no limit on how often or how much the Kensai can use this ability. Even though there's seemingly a cap in place (up to 1 point/class level), I don't see why BASE attack or save wouldn't stack, so just use this ability several times to transfer all BAB and saves to the recipient to build a real monster.
Once you've digested this, think about the Leadership feat. More specifically, think 20th level PC with an 18th level Kensai cohort. Who picks up Leadership himself and has a 16th level Kensai cohort. Who picks up Leadership
again and has a 14th level Kensai cohort. Unfortunately, that's where the chain ends (Kensai cohorts need to be at least 13th level to have this ability). That still leaves us with a 20th level PC who has a BAB of +68 for (close to) an hour. And what will we do with that?
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