Desecration: Worth 5 talent points? (DPS)
Summary: I have a theory that for Unholy Death Knights, 5/5 Desecration is not worth the talent point investment given the Glyph of Scourge Strike and other talents on which those points could be spent.
It's pretty well known that Blizzard balances talents around a 1% increase per talent point - its slightly less known (or oft-ignored) that this is only an approximation, and must be weighed against what other talents could be purchased for the same point expenditure. To complicate matters, glyphs can dramatically affect talent choice and skill usage. Most of the readers here should understand all of this.
So let's look at Desecrate. This is an oddly scaling ability that rewards consistency for investing the full five points. At 5/5, you get a straight-up 5% damage increase, as long as you properly maintain the effect, including standing in the appropriate area. Fewer points spent in the talent offer the same damage bonus, but with a cumulative 20% reduced chance to occur, meaning that if you're lucky, you can get better than a 1% dps increase per talent point, but more likely, over the long term, you'll see a significantly reduced efficiency. If you're a gambling man, that's probably all you needed to hear, but I like to have a little more security than that, especially considering the skill we use to proc Desecration, Plague Strike, isn't going to help you top any dps charts on its own.
Yet there's still no problems at this point - you've got your standard unholy rotation:
1) IT > PS > BS > BS > SS
2) SS > SS > SS
Which you alternate in order to keep up your diseases, automatically refreshing Desecration at regular intervals, and of course, you dump runic power as needed. We'll avoid the issue of movement for the time being - it is important, but its not relevant for now, because at this point, desecration is still doing what it should - giving us a 1% damage increase per talent point.
So let's shift gears for a moment and look at glyphs... unholy isn't drowning in good choices here, but the one that does stand out is Glyph of Scourge Strike, which gives you a 25% chance to apply your diseases whenever you hit with Scourge Strike. This is a good thing because it frees up your runes so that you can convert an IT > PS in your first rotation into a SS when it procs, which should be substantially better damage for the rune cost. The glyph isn't as reliable as I would like, but unholy deathknights really don't have any better choices, and when it does work (and it *feels* like it works often enough to keep this player satisfied - even though feeling is a bad sort of evidence, it is important for the enjoyment aspect of the game) it does contribute a good chunk of damage.
Reliability aside, there's just one problem with this glyph: it works in opposition to Desecrate. If you use the glyph, you're hoping for it to work, but if it does work, you have to ignore the benefit in order to refresh Desecrate, at which point, if you're determined to refresh Desecrate, there's no reason to take the glyph in the first place.
Enter into the arcane combination of factors that makes me doubt the usefulness of Desecrate as a talent:
1) Glyph of Scourge Strike is the best choice of dps glyphs for an Unholy Death Knight - while it may not be optimal itself, which is not to say that it is not a noticeable contribution, there's nothing better worth picking in its place.
2) Glyph of Scourge Strike works in direct opposition to Desecrate.
3) Positioning factors further reduce Desecrate's overall dps contribution by some unaccountable degree.
4) Five talent points is too much to spend on a talent that touts 5% dps if it cannot be guaranteed 100% up-time, and fewer talent points spent result in significantly diminished returns.
5) There are plenty of other talents that can be purchased which must yield at least a similar return without the draw backs.