Idioms and metaphors are difficult to use and awkward to learn. They often use cultural references and unusual words. However they make language more interesting. Some people take the desire to be interesting too far. I strongly suggest that one sentence should not have more than one idiom or metaphor.
Consider the idioms in this sentence: "Pupils become little princes at home with their parents often at their beck and call, all to be able to provide them with a comfortable place to rack their brains." (Advice for students now that school exams are looming, The National, 22 Jun 2018)
First, the sentence above contains a metaphor. A little prince is a child in a rich family who is spoiled, overly-protected and not taught to co-operate with others. Of course such a child grows up to be egotistical, rude and demanding. The Chinese-English version is a little emperor.
Second, the word beck is (a noun) related the word (verb) beckon. To beckon someone is to call them over to serve you, often using a hand signal. A beck is an obsolete word meaning such a hand signal used to summon a servant. However the fossil word (link.mingpao.com/65995.htm) beck is known and used by very few people. The idiom, beck and call, is fairly common among native speakers; it means to have control over every action that person takes and to command their constant attention.
Third, to rack one's brains is to try very hard to remember something. However to rack someone meant to put them on a large medieval torture device and have their arms and legs pulled until they were slowly and painfully dislocated prompting the victim to tell you what you want to know. The idiom rack one's brains (wit, memory) means that the person is thinking so hard it is as uncomfortable as being tortured on a rack. Most people use this idiom without really understanding it.
Try to avoid using more than one idiom or metaphor in a single sentence. Sometimes flowery language is interesting, but too much together makes your sentence difficult to understand.