Flare deals 300% more Damage, its Projectile Speed is increased by 100, and its Cooldown is reduced by 10s.
Every 1.5s your inactive Weapon generates 2-10 Ammo.
Entering stealth below 65% health heals you for 100-500 health.
Increase the ammo count of both of your weapons by 2-10.
Reduce the movement speed penalty of Scope by 20-100%
Reduce the time to swap to your Side Arm by 20-100%
I have made this build mainly to counter flanks like androxus or evie.
Use the pistol and the flare as a main defensive weapon agains't flanks. Going invisible when you are low life should give you what you need in health to survive and give you a fire window to aim a last shot with the sniper to finish them if your pistol is empty.
Do not hesitate to use the flare, it can make more dmg's than the sniper if well used, especialy agains't semi shield champions like androxus or vivian, just aim the their feets.
For the items, I usualy go for caut 2 then agi 1 (agi 1 is really important to compet with the flanks. No need to get more, aiming with the rifle will be more difficult with agi 2 or 3. If you play agains't a buck or another high regen char, caut 3 before agi 1 would be a better option). After that you are free to complement with what you need (caut 3 ,defensive item or kill to heal as regen).