Shadow Fang Damage Over Time

[Rongway]

Each entity has a tick timer, such that every three seconds, all DoTs and HoTs on that entity do their work, so we expect a 21s DoT to tick seven times.

At 40 potency per tick, Shadow Fang will do at least 280 DoT potency on top of its initial 200 potency. Skill Speed increases DoT damage from weaponskills, so it'll do a bit extra for that too. So Shadow Fang is 480 plus speed bonus, assuming perfect reapplication timing. These numbers are normalized to you, if you're comparing only against other NIN actions.

If you want to compare against the potencies of other jobs' actions, remember to apply the 20% bonus from Dripping Blades: 288 DoT + 240 initial, for a total of 528 plus speed bonus.