Echo/Stats

Echoes are essentially the equipment of the characters, which can be farmed in the overworld with a drop rate based on player's current Data Bank Level. Every Echo is assigned a Cost and a Sonata which depends on the Echo type and Rank. A maximum of five Echoes can be equipped on a Resonator at a time. 
==Classification==
Echoes can belong to one of four Classes: Common (Cost 1) , Elite (Cost 2), Overlord (Cost 3) and Calamity (Cost 4). Resonators are given an Echo Cost limit which depends on the player's current Data Bank Level. The total Cost from all the equipped Echoes on a character cannot exceed the player's Echo Cost Limit. The maximum achievable Echo Cost Limit is 12 (unlocked at Data Bank Level 9).
Echoes also have different Ranks (or Rarities). The Rank of a captured Echo depends on the player's current Data Bank Level. Note that Rank and Class/Cost have no correlation. The maximum upgradable Level of an Echo depends on its Rank
Data Bank Level	Highest obtainable
Echo Rank	Highest upgradable
Level of Echo
0-4 	2	10
5-7 	3	15
8-14 	4	20
15-20 	5	25
==Main Stats==
Echoes have two Main Stats. The value of the Main Stats are different per Echo Cost and Rank and are shown below. An Echo cannot have the same Primary and Secondary Main Stat, but its Substats can be the same as the Main Stat. 
Stat 	Rank 2
(LVL 1 - 10)	Rank 3
(LVL 1 - 15)	Rank 4
(LVL 1 - 20)	Rank 5
(LVL 1 - 25)
1-Cost Echo 	1-Cost Echo 	1-Cost Echo 	1-Cost Echo 	1-Cost Echo
HP% 	2.2% - 5.7% 	2.4% - 8.1% 	2.7% - 11.3%	3.6% - 18.0%
ATK% 	2.2% - 5.7% 	2.4% - 8.1% 	2.7% - 11.3%	3.6% - 18.0%
DEF% 	2.8% - 7.2% 	3.0% - 10.20%	3.4% - 14.2%	4.5% - 22.8%
HP 	114 - 296 	152 - 516 	228 - 957 	456 - 2280
3-Cost Echo 	3-Cost Echo 	3-Cost Echo 	3-Cost Echo 	3-Cost Echo
HP% 	3.7% - 9.6% 	4.0% - 14.0% 	4.5% - 18.9%	6.0% - 30%
ATK% 	3.7% - 9.6% 	4.0% - 14.0% 	4.5% - 18.9%	6.0% - 30%
DEF% 	4.7% - 12.3%	5.0% - 17% 	5.7% - 23.9%	7.6% - 38%
DMG Bonus 	3.7% - 9.6% 	4.0% - 14% 	4.5% - 18.9%	6.0% - 30%
DMG Bonus 	3.7% - 9.6% 	4.0% - 14% 	4.5% - 18.9%	6.0% - 30%
DMG Bonus 	3.7% - 9.6% 	4.0% - 14% 	4.5% - 18.9%	6.0% - 30%
DMG Bonus 	3.7% - 9.6% 	4.0% - 14% 	4.5% - 18.9%	6.0% - 30%
DMG Bonus 	3.7% - 9.6% 	4.0% - 14% 	4.5% - 18.9%	6.0% - 30%
DMG Bonus 	3.7% - 9.6% 	4.0% - 14% 	4.5% - 18.9%	6.0% - 30%
Energy Regen 	- 10% 	4.2% - 14.2% 	4.8% - 20.1%	6.4% - 32.0%
ATK 	12 - 31 	13 - 44 	15 - 63 	20 - 100
4-Cost Echo 	4-Cost Echo 	4-Cost Echo 	4-Cost Echo 	4-Cost Echo
ATK 	18 - 46 	20 - 68 	22 - 92 	30 - 150
HP% 	4.1% - 10.6%	4.3% - 14.6% 	4.9% - 20.5%	6.6% - 33.0%
ATK% 	4.1% - 10.6%	4.3% - 14.6% 	4.9% - 20.5%	6.6% - 33.0%
DEF% 	5.2% - 13.5%	5.5% - 18.7% 	6.2% - 26.0%	8.3% - 41.5%
Crit Rate. 	2.7% - 7.1% 	2.9% - 9.8% 	3.3% - 13.8%	4.4% - 22.0%
Crit DMG. 	5.4% - 14.3%	5.8% - 19.7% 	6.6% - 27.7%	8.8% - 44.0%
Healing Bonus	- 8.5% 	3.5% - 11.9% 	3.9% - 16.3%	5.2% - 26.0%
The optimal configuration of Echoes depends on the character used, but generally the optimal configuration uses a 5-piece set bonus with a 4-3-3-1-1 Cost configuration.
==Substats==
Substats are additional stats that are unlocked via Echo Tuning. An Echo can have upto 5 Substats which cannot be changed or re-rolled. Substats roll independently of the main stats. The rolls are fixed and the chances of the rolls appears to follows a Gaussian distribution. The number of possible rolls is 8 for every Substat aside from Flat ATK and DEF which is 4 rolls. The weight of sub stats drop rate are currently unknown and a bigger sample size is needed to draw more conclusions.
Substat 	Range of Values	Median Value
ATK 	50 - 70 	55
HP 	320 - 580 	450
DEF 	50 - 70 	55
ATK% 	6.4% - 11.6% 	9.0%
HP% 	6.4% - 11.6% 	9.0%
DEF% 	8.1% - 14.7% 	11.39%
Energy Regen 	5.6% - 14.9% 	9.6%
Crit Rate. 	6.3% - 10.5% 	8.4%
Crit DMG. 	12.6% - 21.0% 	16.8%
Basic Attack DMG Bonus 	6.4% - 11.6% 	9.0%
Heavy Attack DMG Bonus 	6.4% - 11.6% 	9.0%
Resonance Skill DMG Bonus 	6.4% - 11.6% 	9.0%
Resonance Liberation DMG Bonus	6.4% - 11.6% 	9.0%