Q: Exactly how often can a monk attack with a single manufactured weapon when using the flurry of blows ability? For example, if I have a +1 alchemical silver dagger, and I’m allowed three attacks in a flurry, how many of those attacks can be dagger attacks? What if I have two daggers? How about with natural weaponry, such as a claw or bite? For example, if I have a vampire monk, can I flurry with a slam attack and drain energy multiple times from one living foe? If natural weaponry doesn’t work with a flurry, why not?
A: You can’t use a dagger with a flurry of blows at all. When you use the flurry ability, you must attack with either unarmed strikes or with special monk weapons. There are only six of the latter included in the Player’s Handbook (kama, nunchaku, quarterstaff, sai, shuriken, and siangham). A natural weapon (any natural weapon) is neither an unarmed strike nor a special monk weapon, so you can’t use it along with a flurry.
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It might seem a tad strange that you cannot use a natural weapon, such as a slam or a claw when you can use a monk weapon such as a sai or a kama. However, natural weaponry isn’t as handy as manufactured weaponry. You never get extra attacks from a high base attack bonus with natural weaponry, and the monk’s flurry ability is another way to get extra attacks from your base attack bonus. It’s worth noting here that a vampire monk using its unarmed strike ability is not using its slam attack and cannot drain energy.