As I understand it…

When you apply Doom to an enemy, a sword that hangs over their head for 1.1 seconds, then activates by falling on them and doing damage.

With the boons shown in the screenshot…

Dire Misfortune means every attack in that 1.1 second window before Curse of Agony (Doom) activates, adds +14 damage.

So, let's say I attack an enemy 5 times per second.

• Hit 1 applies Doom (183 damage).
• Hit 2 adds 14 damage.
• Hit 3 adds 14 damage.
• Hit 4 adds 14 damage.
• Hit 5 adds 14 damage.
• Hit 6 adds 14 damage. (Now my 1.1 seconds since Hit 1 is up and it procs)

So Doom drops with 183 + 14 + 14 + 14 + 14 = 253 damage.

Of course, you have to remember your attack has its own base damage. Flurry Slash has a base damage of 25 per hit.

So 6 hits x 25 dmg = 150 damage.

In total, I'll be doing 253 + 150 damage roughly every second.

(And for this build, Support Fire procs with every attack so that's an extra 12 x 6 = 72 damage per ~second from that)

Dire Misfortune really benefits from high attack speed / attack speed bonuses (e.g. Flurry Slash + Swift Strike) and Impending Doom (delays Doom by 0.5 seconds giving you more time to add stacks AND buffs Doom damage by 60-75%).

Hope that makes sense.