Hello and welcome to EpicNPC,
MM is used to ensure delivery of the account, but if chargebacks/recalls occur then your best bet is to file a dispute with Paypal if Paypal was used
To start a MM transaction go to this link:
https://www.epicnpc.com/tradeguardian/
Type the username and the thread link and it'll start a transaction for you once the seller/buyer accepts.
A MM will then come in to handle the transaction
Before you guys are able to trade, the buyer/seller needs to pay a fee
Fee: $4.95 + 6% of item value.
The seller will then transfer the item or account to the MM
The MM will update the password and fully re-secure the account.
The buyer will then send payment directly to the seller using any payment method both parties agree to.
The seller then confirms to the MM payment was received.
The MM will then transfer the item or account to the buyer and help them re-secure it.
You can read more
Here