Korimyr the Rat said:
However, the rules-as-written allow for ridiculous, if not necessarily unbalanced, situations, such as a Lizardfolk Monk throwing five unarmed attacks on top of his claw/claw/bite. Regardless of the language of Improved Unarmed Strike... how is that supposed to work?
Actually, he can't do that. You can't mix Flurry with natural weapons.
That being said, a lizardfolk warrior can do the same thing with Armor Spikes and his natural attacks - 4 armor spike attacks, three natural weapons.
As for how it works, I'd imagine it works in the exact same way a dragon somehow manages to get a claw, claw, bite, wing, wing, tail slap - or a human manages to get a longsword, longsword, longsword, longsword, longsword, shortsword, shortsword, shortsword attack sequence in.
If you can throw unarmed strikes along with your claws and bites, why can't you throw unarmed strikes along with your armed strikes? After all, using a greatsword doesn't tie up your head and your feet, or your elbows and knees. (Hell, there was a great deal of pommel, elbow, and headbutt work involved in historical greatsword combat.)
You can absolutely mix them - you'll just take two-weapon fighting penalties. Note that unarmed strikes are considered light weapons.
If there's nothing stopping you from mixing your unarmed strikes with your weapon strikes, doesn't that make the Ftr1/Monk X with a Greatsword a little overpowered?
Well, you can't use a greatsword in a Flurry, for one ...
Two, he'll never be as good with his greatsword as a dedicated Fighter.
If not, how does that differ from the Thri-Kreen Monk?
A thrikreen has natural weapons; a human does not.