The words trap and entangle were flavor text, explaining how the material does what it does.<br/><br/>Damage reduction is described in this format:<br/><br/>DR 3/slashing and bludgeoning<br/><br/>That means that damage id reduced by three unless that damage comes in the form of of a slashing or bludgeoning attack.<br/><br/>If it said DR 5/Magic, that would mean that damage from a non-magical weapon is reduced by 5.