The short version of what is and is not OK here. The Terms of use are the legal version.
List what you have, not what you are about to buy. If something is damaged, say so before the deal, not after. If you realise you cannot supply something you promised, say so immediately — nobody minds a mistake, everybody minds silence.
Reproductions and custom cards are fine if you say clearly that is what they are. Passing one off as genuine is not, and it will cost you your account.
Accepting a deal takes the cards off everyone else's list. If you have changed your mind, cancel it — that puts them back for other people. Leaving someone waiting is the one thing that makes this whole site worse for everybody.
Meet somewhere public and busy — a mall, a café, outside a shop. Tell someone where you are going. Bring the cards in a sleeve or a folder so you can both check them without arguing about a bent corner afterwards.
If you are under 18, bring a parent or an adult you trust. If the person you are meeting is under 18, expect their parent to be there, and be normal about it.
Use a tracked service for anything you would be upset to lose, and send the tracking number in the message thread so it is on the record. For a first trade with someone new, start with something small — reputation is cheaper to build than to recover.
Arrange the deal in the message thread on the site. If it later goes wrong, that thread is the only evidence either of you has. Anyone who pushes hard to move the conversation somewhere else before agreeing anything is a pattern worth noticing.
No insults, no harassment, no advertising, no messaging people who have said no. Disagreements about a card are normal. Everything else is not.
Every listing, profile and message has a report link, and you can always write to contact@voidalis.com. Tell us what happened. We will look at it and tell you what we did.
Depending on what happened, we may remove a listing, hide something you wrote, limit your account, or close it. We will tell you which one and why, and you can reply to ask a person to look again.