Forgot to answer this part. If the “trick” is known in the art, such that a person of ordinary skill in the art would be expected to know it or be able to look it up without undue experimentation, then the claim should be enabled. Exactly who counts as “ordinary” and how much experimentation is “undue” are judgment calls for the court.
I’m not sure what you mean by a “trick.” If it’s something that a person with ordinary skill in the art would not know or would not be able to find out easily, then it must be disclosed in the patent. A patentee is not allowed to reserve any secrets. That’s the trade-off with patents – you get a limited monopoly, but you have to disclose your invention to the public.