Per your post in the "XML Codes" thread, here's what I was able to figure out (the instructions were in Portuguese I think, but watching the video is fairly easy to pick up):

1. Download and install JPEXS Free Flash Decompiler (link is in the thread)
2. Open Charles, then open MAA.
3. Download "client2.swf" (just like you did for "client", etc.)
    > Go to:  marvelshield/.../2016#########/client/swf
4. Open JPEXS and load the client2.swf file you just saved.
5. In the left-pane navigation tree, go to: scripts / mvcs / commands / lockboxCollection, and select "GetLockRewardIdCommand".
6. In the middle window, scroll to line 37.
    (it should say "var _loc2_:int = this.event.payload["count"];").  Click "count".
7. In the right-pane, on line 37, change "count" to "666" (or "0", or "", or just about anything).
8. Save the file and close JPEXS.
9. Back in Charles, right-click client2.swf, and select "Map Local".
10. Under "Map To", click "Choose", then navigate to your saved copy of client2.swf. Click OK.
11. Close MAA and Charles, clear your web cache and reload as usual.
12. Go to your Collections and open 1 LB at a time (not 10 at a time).  You will get a cover every time without losing any LBs!  Keep opening until you get all 8 covers.