Nightmare Eggshell is up there on our BIS trinkets but not "the" best. I use it purely so I can cross that 32% threshold every minute of every fight on Mythic. It's great to do so, and helps me with regen. I'm lucky I got it out of my weekly +10-12 cache about a month ago.
To be perfectly honest I don't have "any" issues with maintaining resources on a fight. I'll have that incredibly rare occasion where RNG decides I'm its bitch and I'm getting no RE procs, but otherwise I'm fine.
However, this is due to a couple of factors rather than just my trinket: I have the BIS Legendary Belt, I run the standard Runic Attenuation, and any downtime is marginally offset by Frozen Pulse.
But this rolls into the other major issue: talents. I'm glad they're taking a look at talents, and I'm glad that they're reeling in secondary stats, but I am sort of fearful as to what my resource management is going to be like in 7.1.5.
If these talent tweaks can offset it (example: Murderous Efficiency, though in the process of taking that we lose Icy Talons), I'm completely fine with it. I sincerely just hope this works out.
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I'd be happy if they adjusted how primary stats scale with each class, because this has been an issue with DKs since.. well, ever.
We start off the expansion strong. Hell, aside from the tweaks to RNG and some damage buffs, I pull fantastic damage in our raids.
But once scaling gets out of control by the 2nd/3rd tiers due to stat inflation, there's almost no way to avoid us being middle-bottom of the pack.
The good thing about this nerf to secondaries is that it's a "fix" to a stat inflation that's already started to occur with this expansion. However, something else needs to be done in order to fix it popping back up later in the expansion.