Originally Posted by
Belin
If your base haste rating from other gear is fairly low, tie the Shards with PI in a macro. It should give you in the neighborhood of 50% haste for 20 sec (maybe somewhat higher). That will drop your GCD to 1 sec (for quick shielding), Penance cast time to 1.4-1.5, CoW to 1.5-1.6, making you a mean burst healer for emergency situations. If you have it, and you can manage, try to drop a Mindbender in there in the first 5 sec or so. You'll get a ~50% boost to mana generation from that, since its attack speed is based off of your stats. Using Shards in conjunction with PI gives you the (nearly) the full benefit of the trinket plus the advantage of offsetting your increased mana usage through reduced mana costs from PI and possibly boosted mana returns from Mindbender.
Optionally, you can tie AA with this macro or make a secondary macro with it attached for extra throughput by dumping whatever stacks of Evangelism you have when you activate it.
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I find that spirit proc trinkets are great, but have two small weaknesses that often aren't accounted for in spirit equivalency calculations:
The random proc function can result in some undesirable proc timing. For instance, it can proc too early to be really useful on a fight resulting in some wasted mana, even if you're blowing it on purpose to stack Evangelism early. Since I usually stack 2-3 at the beginning anyways, this represents an opportunity cost that needs to be accounted for. Sometimes I'll even have the sucker pop when I'm re-forting the raid or a late rezzer after a wipe and it will still be on cooldown for a minute or so into the fight.
Calculations for spirit equivalent are often based off of the ICD, but at a 15% proc chance, it will take 4-5 casts on average to get it to proc. This easily adds 5-15 seconds to the ICD.
For safety, and to be conservative (to account for proc wastage), I add 20 seconds to the ICD, then divide by the buff duration to get the equivalency. This reduces the value of spirit proc trinkets slightly.