Development and updates on this website have come to an end. There won't be any more update in the foreseeable future.
More details here 
Istvan
Stats Overview
Breakthrough 0, Equipment (Ascension 1+) 1, Affinity 1.
Ascension 0
Min. / Max.
ATK: 478 / 783
DEF: 188 / 285
HP: 1475 / 2296
Ascension 1
Min. / Max.
ATK: 886 / 1429
DEF: 319 / 493
HP: 2582 / 4012
Ascension 2
Min. / Max.
ATK: 1558 / 2072
DEF: 536 / 701
HP: 4389 / 5740
Ascension 3
Min. / Max.
ATK: 2273 / 2823
DEF: 763 / 939
HP: 6307 / 7756
Ascensions
Ascension 1: Specular State
20
30
10
25000
Ascension 2: Radiant State
20
30
10
40000
Ascension 3: Ascended State
20
30
10
150000
Breakthroughs
Breakthrough 1:
HP increased by 250.
200
Breakthrough 2:
Active Skill Enhancement: Changes Active Skill to Preemptive Strike. Available upon entering combat.
300
1
Breakthrough 3:
Increased by 250+5% Basic max HP.
350
1
Breakthrough 4:
Increased by 30+5% Basic DEF.
400
1
Breakthrough 5:
Active Skill Enhancement: Reduces skill cooldown by 1 round.
500
1
Affinity
Lv.1 We Might Have Met Before
Total Exp:
0Total bonus stats:
ATK: 0DEF: 0HP: 0
Lv.2 Lukewarm Greeting
Total Exp:
100Total bonus stats:
ATK: 6DEF: 3HP: 30
Lv.3 Self-evident Rapport
Total Exp:
300Total bonus stats:
ATK: 12DEF: 6HP: 60
Lv.4 Indissoluble Friendship
Total Exp:
600Total bonus stats:
ATK: 18DEF: 9HP: 90
Lv.5 Where Halos Converge
Total Exp:
1100Total bonus stats:
ATK: 25DEF: 12HP: 120
Lv.6 You Have My Back
Total Exp:
1700Total bonus stats:
ATK: 32DEF: 15HP: 150
Lv.7 Intertwining Twin Stars
Total Exp:
2500Total bonus stats:
ATK: 40DEF: 18HP: 180
Lv.8 Light Beyond Startrails
Total Exp:
3500Total bonus stats:
ATK: 48DEF: 21HP: 210
Lv.9 Resonating Radiance
Total Exp:
4700Total bonus stats:
ATK: 56DEF: 25HP: 250
Lv.10 When All The Stars Shine
Total Exp:
6200Total bonus stats:
ATK: 65DEF: 30HP: 300