Terra Battle Skill Boost Gain Guide

Terra Battle Skill Boost Gain Guide by Kivanc

Before anyone attempts, let me also stress that none of this information is gained by hacking the game. It is decompilation and examining the source code. Any discussion or attempt of hacking / modifying the source code is strictly prohibited and will result with banning. These guides are created to increase our knowledge about the game. All information on these guides can also be approximated by gathering data community-wise and then examining this data.

How Skill Boost is Gained

As we all know, every time a character activates a skill in a battle, there is a chance that this character will gain a skill boost. But how does the game compute this?


The game uses the following formula to compute the probability of getting a skill boost.
For a character and for a phase (more on this later):

P(skill boost) = 0.02 / MIN(base probability of all skills activated on this phase).

English translation: Get all skills that are activated by that character. Filter the ones that are for the current phase (more on this later). Get the base probability of the skill that has the lowest base probability. Divide 0.02 by this number.


Bahl’s Gigasword and Megasword skills are both “attack” phase skills.

If Bahl activates both these skills, P(skill-up) = 0.02 / 0.4 = 0.05 = 5%
If Bahl activates only Gigasword = P(skill-up) = 0.02 / 0.4 = 0.05 = 5%
If Bahl activates only Megasword = P(skill-up) = 0.02 / 0.5 = 0.04 = 4%

How to use this information?

Well, unless your characters skill boost level is 0%, it is ALWAYS better to select skills with lower base activation rate for skill boost farming. For example: Bahl, skill boost level: 50% Skills: Megasword vs. Gigasword.

Megasword activation rate: 50% + 50% = 100%
Gigasword activation rate: 50% + 40% = 90%

P(skill-up, megasword) = 1 (guaranteed activation) * (0.02 / 0.5) = 0.04 = 4%
P(skill-up, gigasword) = 0.9 (activation rate) * (0.02 / 0.4) = 0.045 = 4.5%

Conclusion: selecting gigasword increases your chance to get skill boost compared to megasword.

Note: If the character is at 0% skill boost level, the probability of getting a skill boost for all skills are the same (balanced with activation rate)

The second way this affects you is that once you reach guaranteed activation for a particular skill for a phase, there is no need to include other skills of the same phase while skill boost farming. For example, Bahl’s Terasword and Attack 10%+ (first job) skills both have 30% base chance and they are both attack phase skills. So, if your Bahl has 70% SB, then selecting only one of these skills is equal to selecting both since both skills will activate at all times, however skill boost gain probability for attack phase will be calculated only once.


This section is not finalized yet as the code is messier. Currently, there are three known phases where skill boost calculation is done: attack, heal, and counter attack. At this point, we don’t exactly know which skill belongs to which phase, however it is in general possible to approximate by watching when the skill is activated in-game. For example (all approximations):

  • Attack phase: Any skill that deals direct damage to the enemy, any skill that buffs the character.
  • Heal phase: Any active heal skill or any remedy skill.
  • Counter attack phase: All counter skills and capsule generations.

In other words, for each character that managed to activate at least one skill that belongs to each phase, a separate probability of skill boost is calculated.

How to use this information?

If a character has skills from different phases, it is ALWAYS better to equip different phase skills (and the ones with lower base activation rate) instead of same phase skills.

For example, for Yukken’s Negotiator Pro (30%, attack), Teraspear (30%, attack), Self-heal (30%, heal) skills, if you can only get two of them, you should select one from attack phase and Self-heal since when Yukken is 0% SB:

P(skill-up, Negotiator Pro + Teraspear) = P(skill-up, Negotiator Pro) + P(skill-up, Teraspear given no Teraspear) = 0.3 * (0.02 / 0.3) + 0.7 * 0.3 * (0.02 / 0.3) = 0.02 + 0.014 = 0.034 = 3.4%
P(skill-up, Teraspear + Self-heal) = 0.3 * (0.02 / 0.3) + 0.3 * (0.02 / 0.3) = 0.02 + 0.02 = 0.04 = 4%

The situation becomes more dire when Yukken has higher skill boost level initially, let say for 70%:

P(skill-up, Negotiator Pro + Teraspear) = P(skill-up, Negotiator Pro) = (0.02 / 0.3) = 0.067 = 6.7%
P(skill-up, Teraspear + Self-heal) = (0.02 / 0.3) + (0.02 / 0.3) = 0.067 + 0.067 = 0.133 = 13.3%

Additional Notes

  • It is confirmed that the maximum skill boost you can gain per character in a dungeon is 0.2%.
  • It is confirmed that equip skills (skills with no activation rate since they are passive buffs) do not get any chance to get skill boost. In other words, they are useless for skill boost farming.
  • Capsule usage might affect skill boost gain (either as a part of existing phases or as a new phase) but we are not sure about this.


Mistwalker can change the algorithm used to compute skill boost gain rates at any given time with a direct or stealth update. Although we will do our best to update the information when such an update happens, Terra Battle Forum takes no responsibility due to potentially stale information provided in this guide.

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