The Torch God is summoned when the player places around 100 of any type of torch anywhere below the surface at 200 blocks deep.
Open areas are useful as you have a lot of space to move around.
Different torches have different flame colors. Crimson Torches are a bad idea to use, as the flames are almost impossible to see. Using Ultrabright Torches will give you an easy time to spot as they have very bright flames.
Creating a loop of Minecart Track around the torches can be an effective way to dodge the fireballs easily.
Circling the flames using Rope and Platforms is an easy way to avoid being hit.
An Ultrabright Helmet can be used for greatly increased vision at the cost of a possible higher defense helmet.
Swiftness Potions are a good source of speed. It is used to dodge flames quicker so you don't get hit.
Enabling autopause will be helpful to dodge the fireballs easily by planning your next move every time you open your inventory.
Using Peace Candles will stop the extra enemies from spawning, allowing you to focus more on dodging.
The projectiles can be easily avoided by placing all the torches in the center of your arena, building a large open space underground and moving in one direction (near the edges) during the event.
Good additions to your arena are a rope ladder, as dodging the flames vertically is easy. Non-torch light sources, like lanterns and campfires, will help you to see better.
If you make a house near the area you plan to fight, you can move the nurse in, thereby negating the need to dodge the projectiles at all, so long as you have a hook in order to negate knockback.
If you set your spawn point with a bed nearby you can continue to fight even after you die.
If you are having trouble beating the event by conventional means, a viable strategy is to build a 10 by 10 torch square with a minecart track circling it. Leave one torch out of the square until the track is complete.