Critical Multiplier Maximization Question

Quick question: I was wondering what are all the ways to increase the critical multiplier.

I have been theorizing a Shadow Assassin build and looking for ways to maximize the critical multiplier using all and any feats available (including fighter feats).

Resurrecting this because I'm looking for this myself. All I can find is a Mythic Feat. Any know of anything? Third party stuff is welcome!

The 4th level Kensai thing increases the multiplier by 1 at the cost of 2 ki points. Then at level Twenty, IIRC they get the Fighter Capstone, which increases it by another 1. And of course the Mythic Improved Critical.

Barbarian gets a crit multiplier improvement as well.

Thanks for the replies guys. Unfortunately those options are a bit too deep in classes to be useful for my purposes (though that does make a bit of sense).

Well, you can always use a Lance while mounted and the Spirited Charge feat chain. Without anything else, that'll give you a x5 multiplier. (Lance is base x3, double damage on charge makes it an effective x4, Spirited Charge makes that x5; using PF's wonky multiplication rules, of course)

One other way is using mythic death from above. I believe it offers a boost, of course use a weapon with a good crit multiplier. I think there may be a trait in wrath of the righteous (again mythic ). That may raise it at later levels 'stolen power' or something like. Hope this helps.