I am in a hobby band with a bunch of mates. We chose a name that has a passing similarity to an infamous movie monster. We recently started a Facebook page and created some artwork using imagery that could suggest the monster in question. In one instance part of the actual movie monsters, the body is visible, albeit heavily modified with the head obscured and reduced to black and white. This afternoon, I received an email from a legal firm purporting to be the Australian representative of the rights owner of the beastie in question, containing a cease and desist letter demanding we don't use his image (fair enough) plus sign an undertaking not to ever create images that could infer the monster's behaviour. I'm happy to remove any pictures, but am I required to sign an undertaking, the wording of which is quite generic? The wording is "In consideration of (the company) not commencing immediate legal proceedings against me, I Hereby undertake to: myself, my employees, agents or otherwise whosoever, immediately cease and, for the duration of the copyright in the character, desist in reproducing or publishing in any manner the character, anything substantially similar thereto, or any other imagery attributable to the character and their films, or doing any act comprised in the copyright". How do I respond, please? I've removed the imagery.