Unerring Vision - Disc

[Ezekiah]

Chalice + HLG and then gemming a secondary stat or straight int (you can sim for yourself to determine what build you want to go, although I'd discourage even bothering to sim straight int atm) is going to net you better results than running that trinket.

Edit to expand:

With HLG heroic TF, because I'm lucky, I am able to run 10k spirit and never go OOM, even on heroic Megaera with really aggressive healing. The value of HLG heroic averages out to just below the value of every single bit of spirit I can put in my gems, and that's a true story (except it's total RNG, but you can rely on at least ~2.5k spirit value on heroic I have found. So it just comes down to unerring vision vs chalice. Both have the same int values, so it's just the procs. Here's the problem, though. The dps trinket has an absurdly low uptime, and controlling its proc is difficult. During intense damage, you're going to be using spirit shell preemptively, and then t6, PoM, PoH and offensive penance. Only one of these even has a chance to proc the trinket, unless you're running divine star/halo and it hits. You're much more likely to see a proc during a lesser damage phase when smiting, where it really isn't going to do you much good.

Chalice, on the other hand, is much more likely to proc during intense damage, because you're chain casting heals. Don't get me wrong, it's still a shit trinket, but it beats every other option. Arguments for Heroic Suns 2/2 are well made, but I do not have that option and would find the regen superfluous anyways.

Oh, and one last note. The LMG (healer version, same arguments for it over dps really) is actually amazing. Pop T6 plus a PW:S or two during it if you can control it and enjoy that insane free healing, else just let it reduce your mana usage without changing your priority if the damage is intense. Point is, my experience is with having the meta gem. You may find two regen trinkets far more optimal if you do not have it.