First step is easy. Wipe all zeny, then implement sales tax. That's the only reliable way of removing zeny from the server and should greatly slow down inflation.
Second step is even easier. Wipe all MvP cards. Put 1% MvP card in loot boxes. Tell kRO this and they might send new updates to us. The more P2W iRO is, the more likely kRO will give us some -_- they have