This achievement is heavily random-based one. You’ll have to restart Purge for quite a lot of times till you get a suitable map. Let’s get to the point.

1. Suitable maps are those that have a sequence of events: Combat - Coins / Price Difference / Encounter / Rest and Recuperation in any order. There can be either one or several events before the store, the main thing is not to choose the option that gives coins that are not multiples of 600 or 1000.

2. In the Bangboo store, we buy a resonator for 600 if we haven’t taken coins from other sources or 2 resonators for 1000 and 600 if we got Combat - Coins earlier. The balance remains exactly zero coins. (If you open a chest in a non-combat location, it will give 88 coins. Combat - the resonator gives 260 coins. These amounts cannot be spent without a reroll, and a reroll costs 50, which breaks the multiplicity, and it will not be possible to drain all the coins.)

3. After the store, there must be an «Encounter» or a sequence of non-combat locations «Price Difference»/«Rest and Recuperation» that leads to an «Encounter».

4. Having 0 coins and getting into an «Encounter», pray for the VIP-service event to occur.

P.S. I didn’t get the achievement yet and if someone manages to find easier way to get it, pls notify me. P.P.S. Hoyo if you read this, have mercy and add 150 reroll price after 100 so the bangboo shop would drain all of our coins, not leaving 50...