The Drunken Lizard Pub

I found the hidden guild and one of the guys told me to search for the assassin in Port Kuundad's sewers. I went down there and explored everywhere, the only thing I found was some kind of puzzle with four chest and clues about what to put in them. Does anyone know what to do here?

Also I've ...

Yeah I noticed the same thing, I ended up taking them from towns and dungeons. Once I got Gravedigger's Flame and Cat's Eyes it didn't matter though...