a poisoned chalice
Something that initially appears to be good, wholesome, or positive, but is really harmful. Primarily heard in UK. We thought the change in leadership was going to have a positive effect on the organization, but it turned out to be a poisoned chalice.
a poisoned chalicemainly BRITISH
If you describe a job or an opportunity as a poisoned chalice, you mean that it seems at first to be very attractive but in time will probably cause failure or trouble. She claims that the president appointed his former rival only in the belief that he was giving him a poisoned chalice and that he would not last more than a year. The contract may yet prove to be a poisoned chalice. Note: A chalice is an old-fashioned cup or goblet, usually made of metal and shaped like a wine glass.
a poisoned chalicesomething that is apparently desirable but likely to be damaging to the person to whom it is given.
1998 New Scientist Anyone who discovers a superconductor that works at room temperature may be handing the world a poisoned chalice…the material might be too toxic to be usable.
a poisoned ˈchalice(especially British English) a thing which seems attractive when it is given to somebody but which soon becomes unpleasant: He inherited a poisoned chalice when he took over the job as union leader.
A chalice is a large cup for holding wine.