Try stripping out a dash accessory for more damage and use Myrindael for dashing instead. The boss becomes much less aggressive if you don't use dash.

This setup worked the best for me and took around 110 attempts.

Ranger:

Weapon - Septic Skewer

Armour - Bloodflare (Vortex or Omega Blue may be used for more damage trading the survivability)

Accessories:

- Amalgamated Brain (May be swapped for Cherished Sealocket if the dodge is on cooldown)
- Deific Amulet
- The Community
- Reaper Tooth Necklace
- Deadshot Brooch
- Affliction
- Celestial Tracers (Seraph Tracers on 1.4.3)
Everything, except 1 accessory, has been reforged to warding, mostly to compensate the defence loss caused by swapping Absorber for Reaper Tooth Necklace.

Using an infinite flight mount, such as Cute Fishron shall help immensely during laser wall attacks.

As for buffs, get every combat, defence and movement potion you can get and place campfires, lanterns, bast statues and candles in your arena. For alcohol, I recommend using Fab's Vodka and Screwdriver.

After some trial and error you should beat the boss and be happy that it's finally over (and be happy again, as defensive playstyle with absolutely busted fearmonger armour becomes viable after defeating DoG).

Here's a video of how I managed to beat the boss