Wizards of the Coast doesn’t allow for proxy cards in official tournaments. That said, most playgroups are perfectly fine with using proxies. If you play with a closeknit, regular group we recommend talking to your MtG group to get their take. If you are lone wolf player who joins commander night and plays in FNM we definitely recommend proxies. They can make your deck far more competitive on a budget, and it’s extremely unlikely that anyone will know or care that you are using proxy cards.