Silas' spell seems to have a greater effect as magic meets magic, causing the white chain to glow an almost blinding white before it to overcomes the assault made against it. Barok simply sighs and takes another glance at the mephit.
DM's Hint: Before we go back to town, or throw mephits into magical chains, I would like to remind that group that the mephit said that the chains must be overcome or slackened. Obviously the chains are bound with elements that are stronger than what you have thrown at it thus far, so maybe you can continue your attacks on only one chain instead of dispersing your attacks on the lot of them, or there is a way to cause them to loosen instead of being broken... they are being held by three gnome-sized statues.