I'm subpoenaed to go to court as a witness for the state, what will happen if I plead the 5th?

You need to speak to a qualified criminal defense attorney near you. Normally, you cannot get out of answering a Subpoena and the penalty for not appearing is a potential Contempt of Court citation which could land you in jail until you comply. Or a material witness Subpoena could be issued against you which could get you arrested and brought before the Court until you do testify. Being offered immunity means that you cannot be charged or tried for anything you testify to, nothing more, so that doesn't get you out of it either. Speak to an experienced criminal defense lawyer who can tell you the consequences of not appearing or pleading the Fifth. Good luck.

If you received a subpoena you must appear. If you fail to appear the Court can issue a bench warrant, and then find you in contempt. You have your 5th Amendment right against self-incrimination. However, if the State grants you immunity, or agrees not to use your statement in a subsequent criminal proceeding, then you can be ordered to testify, and failure to testify makes you liable for contempt charges.

If you take the 5th and they offer you immunity, you must testify or you will be incarcerated. You can't get out of it without going to jail for contempt.