How many of these can you get in one run?

I believe the highest amount you can get per run is two. One from the basket and one from the goblins cache.

where is this? random? or a serton spot? is it random proc also? anyone?

NO!!! It puts the tannin in the basket or it gets the mallet again!

ILOLD! classic Silence of the Lambs rip off =D

The tannin basket is up the first ramp after you get to Knot