One of the biggest challenges with the new way DoTs (and HoTs) work in Cataclysm is knowing when you’re at enough Haste to make it worth your while to add more and get extra ticks on your spells, or when it would be better to switch over to a different stat like Mastery or Crit. This is further complicated because each spell has a different breakpoint or plateau due to their duration and intervals, so you can’t just say there’s a set Haste level for your class – it all depends on what you’re casting.

The formula for computing the number of ticks is relatively straightforward:

Round ( Base Spell Duration / ( Base Tick Time / (1 + Haste %)))

In other words, take the base tick time, modify it with haste, then see if the base duration would round it up to an additional tick.

Straightforward doesn’t always mean simple, though. In order to make decisions about how much Haste to stack, you’ll want to look at all of your DoTs and see where the sweet spot is for *you*.

Recognizing that some people are more comfortable with math than others, I went ahead and built a spreadsheet so that you could see how your spells would work with Haste. Cyn’s DoT/HoT Haste Calculator:

- Lets you configure four spells with different durations and tick times.
- Gives you a place to enter your current Haste percentage and see its effect on each spell and the GCD.
- Lets you see how much Haste rating you will need to reach specific Haste percentages at level 70, 80, and 85.
- Provides a table of Haste values from 0%-50% with related values for each.

To use it, download the file and open it with the spreadsheet program of your choice. If you don’t have one, I recommend the free OpenOffice suite. Change the DoT1-4 values to match the values for the spells of your choice, then put your current Haste value in the big yellow cell that says YOUR HASTE % HERE. The values should fill in.

Here’s what it looks like, if you don’t want to fire up Excel or OO:

I debated putting in a duration calculator, but it cluttered things up too much for a 1.0 release. I’d appreciate any feedback you might have on this spreadsheet. Corrections, comments, whatever, let me know!

(And for the Warlocks out there, I’m sure you see that the default DoTs are: Immo/UA, Corruption, BoD, BoA. Just as it should be.)

**Update 12/31/10**: I’ve updated the spreadsheet to version 1.1 to include Hamlet’s breakpoint math, below. (Thanks, Hamlet!) There is a new section that shows you where the first 4 ticks are added to your DoT/HoT, as well as the next Haste value you will need to reach to gain an additional tick.

**Update 1/2/11**: Updated to version 1.11. Fixed a bug in the table, thanks Hylix!