I was killing 8 "a ravenous dock rat" that I saw on the docks. Brutus spawned at neg 191, pos 288. I was only there for 1.5 hours. He dropped the 1HB, which is what I was looking for. I guess I was lucky.
location was n36 x p425 x 0. ph was the ravenous rat that spawns there obviously ) warpwood darkclaw dropped for us.
got him..3 more times too. at location n185 x p280 x 0 and at n25 x p325 x 0 and at p5 x p30 x 0. 4 diff spots. all ravenous rat phs. i would just cycle around the docks killing them all and eeventually he spawened in the various locations. good luck.