Seven Deadly Sins Grand Cross gear sets effect are important to you because it can boost the character status. It will help you clear the chapter easily, even take your enemy down easily at PVP.
Gear Set Attack (4 sets)
Bonus set effect +20% Attack
Get it from Chapter 1
Gear Set Crit Damage (2 sets)
Bonus set effect +20% Crit Damage
Get it from PvP
Gear Set Crit Defense (2 sets)
Bonus set effect +40% Crit Defense
Get it from PvP
Gear Set Crit Rate (4 sets)
Bonus set effect +30% Crit Rate
Get it from Chapter 4
Gear Set Crit Resistance (2 sets)
Bonus set effect +30% Crit Resistance
Get it from Chapter 5
Gear Set Defense (2 sets)
Bonus set effect +20% Defense
Get it from Chapter 2
Gear Set HP(4 sets)
Bonus set effect +20% HP
Get it from Chapter 3
Gear Set Lifesteal (2 sets)
Bonus set effect +15% Lifesteal
Get it from PvP
Gear Set Recovery Rate (2 sets)
Bonus set effect +20% Recovery Rate
Get it from Chapter 6