I can’t think of any reason why it would be inadvisable to cut off billing to an MMO subscription that was connected to a privacy.com card. Is there any basis for your concern? Do you know of someone who had “prevented Blizzard from billing them for WoW” on their credit report?

I can’t say I’ve ever had an MMO subscription - or any prepaid account, for that matter - show up on my credit report. Or that I know anyone who has. Even prepaid credit cards don’t show up on your credit report.

If a game, site, or app subscription fails to bill, the recourse the provider has is to cease providing the service. Standard industry practice is to suspend service and send out a notice, attempt re-billing a couple times, and to them consider the subscription canceled.

A debt can show up on your credit report, even if it’s not associated with a loan or line of credit… But with a prepaid account, like an MMO subscription, you’re never extended credit and you never incur a debt. The exception would be if you signed a contract for your prepaid account stating that you’d maintain it for a certain amount of time (common with phone plans, internet plans, leases, some shady gym memberships, etc.) or you caused damages to the provider. Without such an agreement, there are no damages from just causing them to be unable to continue billing your credit card. If you were paying by check or disputed an already posted payment, that would be different - but neither of those are relevant here.