First some facts:
* Fang of Vog can inflict fire to the player with the charge attack.
* Fire resistance lowers the fire duration, number of fire ticks and damage per tick.
* Universal damage bonus applied to fang of vog (e.g. from skolver / black kat / slash module) increases damage per tick.

Some tips:

* Self-fire ticks will reset your charge meter to half, so timing it right can speed up charge time, timing it wrong can slow you down. After releasing a charge that sets you on fire, you can follow-up with 2 hits (the last of which will be considered an End of chain hit, dealing more damage) and charge again. The 2nd fire tick from the first charge will then let you skip half the charge up time for the next charge.

* The lowest amount of fire ticks is 3, the breakpoint for this is +6 fire resistance. Further increasing fire resistance will still reduce the damage per tick. As with any status, +10 resistance is max resist. Without universal damage bonus, at +10 fire resist, you will receive 3 ticks dealing about 1.45 bars of damage each. With +6 dmg bonus and +10 fire, you will receive 3 ticks dealing about 1.8 bars of damage each.

* You can avoid a fire tick by dashing at the right time. Another way to skip a fire tick is by overwriting the 3rd tick with a new charge.

* Damage bonus against specific monster families is desirable with Fang of Vog. Universal damage bonus increases the damage from self-fire, while monster bonus damage does not. The most important families to fight are undead, construct and slimes. Fiends are next because they are often paired with undead and Trojans make a good target for FoV. After that it doesn't matter as much, but Gremlins are often paired with constructs. Beasts are the least important monster type to cover. Pet perk and UVs along with certain armor pieces are possible sources of monster specific damage bonus.

I keep some notes on this wiki page: https://wiki.spiralknights.com/User:Waterbeat/Fang_of_vog