I’m going to copy/paste a post by mrboh in the forums. Huge props for this awesome tool! Use the previous link for support or questions/feedback!

Hex: A Death Knight Analysis Tool v0.1.0 BETA

Download link: http://www.ellipsoid.org/hex/setup.exe

Introduction
Hex is a tool designed to allow experimentation with the various Death Knight talents and abilities. Hex is, for now, based around the parameters of a level 55 Death Knight only. This is because the vast majority of testing so far has been done with starting level characters and extrapolating the known information (ability base damage values, scaling factors, etc) would involve wild guesswork at best.

The tool allows you to see how individual abilities, as well as your overall DPS, vary based on talent choices and cast rotation used. To do this, Hex generates a sample combat log intended to mimic an in-game combat log as closely as possible. In ‘Target’ mode, attacks are made against a target with specified AC and HP until either the player or the target dies. In ‘Loop’ mode, attacks are made until the specified duration is reached. Target mode can be used to test combat rotations for leveling, while Loop mode can be used to calculate average total DPS. All parameters used to calculate the log are based on known starting DK values, with a small amount of guesswork involved for some stats. The DK is assumed to be attacking an equal-level target from the front (ie. leveling).

Installation
Click the link at the top of the post to download the installer. Hex requires the .NET Framework v3.5 and will automatically download and install this if you do not already have it.

Notes
Aside from the fact that many talents are not implemented yet, this is purely a BETA release so please bear in mind that things are still being tested and fixed. Hex will automatically check for program updates when it starts so once it is installed you can easily stay up-to-date with all the latest fixes.

Hex started out as a spreadsheet but the complexity of testing cast rotations meant that I turned it into a fully-fledged program instead. The disadvantage of not using a spreadsheet is that it is not immediately apparant how damage values are calculated so I would encourage people to double check calculations themselves if they are not sure.

Again, to leave feedback or ask questions use this thread in the forums!