Originally Posted by
Demonolotion
Firstly, you either had a shitty previous life or your next one is going to be terrible, because 2 legendaries in 8 hours? It took me 20 days of played time to get my second - and I have been *blessed* with the legs and ring.
Depends on your exact situation - if you have 3 shards as Call DS comes off CD you shouldn't push for the 4th shard - DS is your best shard spender, and it's perfectly acceptable to go DS - (3) HoG - DE, rather than feeling you have to go DB - DS - (4) HoG - DE every time. That way you don't ever risk wasting a shard with a proc anyway. It also depends where on your rotation you are - if you're in the general rotation phase you'll find breaking your cast is fine. I doubt it's a significant DPS impact either way - I've not done the maths, but the extra imp casting for 12s is probably a small DPS gain for a single GCD.
However, if you're in the midst of your TKC set-up it's very different. You should have this section of time optimised down to a GCD, so that you are able to cast TKC +/-0.5s of it's CD. Breaking a cast during this section of the rotation costs you a GCD, and it's a GCD you already have ear-marked for something else, so you're likely facing adapting your most important cast sequence on the fly, without breaking your stride. If you drop 4 empowered imps out of your window because of a lost GCD you tried to squeeze back in that hurts a lot more than wasting a shard. If you end up with 4 imps and 2 DS (+2 imps) all unempowered, rather than 3 imps, 2DS (+2 imps) empowered, I suspect it's also going to be a DPS loss.
As for DC as a talent... baseline haste is relevant.
At 39% (12.5k) haste - about as good as it gets right now - you're going to have time to hit 2x4 shard HoG and a call dreadstalkers (with DC if have no shoulders, or with shoulders), but you're not going to have time to benefit from the extra two shards as there's no time to hit another HoG before you have to hit TKC.
At around 11k haste, you'll probably find you can hit a 4 & 4 when DC procs (and have an extra shard you can't use) or a 4 & 3 when it doesn't, so the benefit is... about half what it could be. The only time DC becomes relevant at this point is during the hero phase. You'll be able to push from 12 imps (including Imp DS imps) and 2 DS to 14 imps and 2 DS.
While you're down below 10k haste, you're probably going to want DC all the time, because it's essentially buying you two extra imps/shards with no real wastage when it procs, there may be a sub-optimal haste bracket for hero phases, but meh you'll get 4/4/DS minimum.
For the record I despise DC - it's a 20% proc chance that goes on scream-inducing cold-streaks far too often in those windows where you're setting up TKC - I've fired off five consecutive 4xHoG without seeing a proc (I make this about a 0.7% chance, so the odds of it happening at the exact worst moment that it always seems to happen in - <10s left on TKC - is somewhere around 0.2%). And there's no balance to this as there's no such thing as a hot-streak - it just procs while on CD without any ability to use the proc any sooner, and all a subsequent proc will do is extend the DC window. As such, as soon as you have the combination of shoulders and sufficient haste, it's worth dropping it. Hell, just run without a talent in T15 instead and remember what your life was like when you were a happy young warlock with none of these concerns.
A simple redesign of this talent to work like Agony shard generation (i.e. you get a proc guaranteed if you generate 5 shards during its CD, and at worst, you're only ever 5ish casts away), would do a lot to smooth out its inherent RNG bullshit.