Skip to content

Letter to Summoners


Dear Summoner,

Thank you for your support in the 7th year of Tower of Saviors. We continue to make every effort to bring you a better gaming experience. In such regard, we have made the following adjustments.


Completed Tasks:

1. Optimize bundle download process

– Only necessary bundle will be downloaded for every update

– Save 20%-30% data consumption in average


2. Remove unnecessary bundle

– Players can “Check the bundle” in the “Setting” to remove unnecessary bundle

– Solve the issue that TOS app occupies a large amount of storage


3. Revamp website framework

– New framework can debug effectively and provide accurate tests

– Step up webpage security to avoid loopholes


4. Testing Servers

– Allow the engineers to fix issues in the new version as soon as possible

Ongoing Task:

1. Optimize and revamp servers

– Save daily alteration time to avoid mistakes

– Increase server capability to handle heavy traffic

– Expected to finish in months

Completed Tasks

1.1 Optimize bundle download process

The bundle download in version 18.2 was optimized to avoid unnecessary data consumption. Every version update only the required bundle will be downloaded. Our records showed that Android, iOS and APK version players can save up to 20%-30% data consumption after the optimization.


1.2 Remove unnecessary bundle

Over years of developments and updates, some in-game resources may inevitably become unnecessary. First, we’ve already removed these resources in the servers to prevent players from downloading these old files. Also, we’ve set up a new function to check the bundle.


This function allows players to remove redundant in-game resources manually, to reduce the storage size that TOS app occupies. We suggest every player to remove the unnecessary bundle once (“Setting” -> “Check the bundle”). If the app is over 1.5 GB, you can do it again.

Image from iOS (21)

1.3 Revamp website framework


We’ve learnt a tough lesson about the “Jumbo Lucky Draw” website before. And we apologize for letting players down in the incident.

As the Taipei Game Show was cancelled, we decided to create a “Jumbo Lucky Draw” website to compensate for our players. The limited time constraint has led to some website loopholes.

To avoid the same mistake, source codes and logics were rebuilt in a week, incorporating the latest website framework to set up the “Jumbo Lucky Draw 2.0” website. The new framework can effectively debug and provide accurate tests. Website security was strengthened to avoid loopholes, Server instability has resulted as we launched the “Jumbo Lucky Draw 2.0” website on 20 Feb due to heavy traffic. The issue was fixed that night.

1.4 Testing Servers


Testing servers were added in Dec 2019. Testing servers act just like the actual TOS app itself. We can provide testing contents to qualified external testers before new features or characters are launched. The purpose is to find out issues in the new version and fix them as soon as possible.

Testing servers started working from Dec 2019 – Jan 2020, 1.5 week. 10 testers were involved to test the battle screen ratio in v18.3, existing character skills display and functions. Totally 16 issues were found, which were all fixed in the version. We’ve conducted a recruit in Feb 2020. Over 10 testers were selected and the total number has increased to 30. In v18.4, we’ve found 16 issues in the drawing machine and server optimization. Our engineers were handling the bugs.

In future, more testers will be recruited for character skills and new features. We’ll be conducting another recruit in Mar 2020.

2. Ongoing Task

2.1 Optimize and revamp servers


Due to increasing in-game contents, server burden becomes heavy. To prepare for the increasing traffic, we’ve conducted many revamps and optimizations for long-term development. It’s expected to finish in a few months.

First, we will simplify server source codes. Due to a large amount of the codes, debugging, alteration or adding new features without any mistake is not an easy task. Therefore we start reviewing the framework of the source codes, separate and simplify them. By removing obsolete codes, more time can be saved and fewer mistakes will be made.

Second, to reduce system burden, we will take data records and analysis systems from game servers into standalone servers and databases. It can reduce the consumption of API server and CPI & RAM, so as to enhance database server capability.

Each optimization requires further tests and adjustments. We will provide pilot optimizations step by step and adjust based on user data. 

3. Game Data

3.1 Hours of Issues


In v18.2, players were unable to login the game as the servers overloaded for 2 nights. In v18.3, during the 7th anniversary and new black-gold “Xiang Yu” events, the overloading situation happened.


18.2 Issues:

– 13 Dec 2019, 22:10 – 22:20

– 15 Dec 2019, 19:06 – 19:43

18.3 Issues:

– 27 Jan 2020, 00:29 – 00:37 (7th anniversary reward)

– 5 Feb 2020, 16:00 – 18:16 (Xiang Yu available)

– 8 Feb 2020, 00:19 – 00:56 (Jumbo Lucky Draw)

– 4 Mar 2020, 05:00 – 11:30 (DNS error)

3.2 Number of Known & Fixed Issues



Some known & fixed issues in v18.2


  1. Unable to connect to server” dialogue may appear wrongly
  2. Activating the active skills of “Kortopi” & “Grand Sage Molly” at the same time leads to game crash
  3. When using “Leader of Phantom Troupe – Chrollo” as leader and ally, restarting game during battle will lead to game crash


  1. Monster image will become extremely large during battle in certain situations
  2. When “Prize Point” filter is applied in Rewards page, tapping “Collect All” will lead to game error
  3. The team skill effect “Non-attributive Attack” of “Heated Fluorescence – Amber” cannot be benefited by the active skill of “Unraveling Jealousy – Malachite”


Some known & fixed issues in v18.3


  1. The confirm button of claiming rewards may disappear
  2. Active skills that add extra 3 rows of Runestones are not working on tablet
  3. Diagonal spin becomes more difficult


  1. When “Ultraman Zero” or “Ultraman Tiga” perform switching, the transformed “Ultraman ORB” will lose its effect of transformation
  2. Unable to connect to server” dialogue may appear wrongly
  3. Activating the active skills of “Kortopi” & “Grand Sage Molly” at the same time leads to game crash
  4. When using “Leader of Phantom Troupe – Chrollo” as leader and ally, restarting game during battle will lead to game crash