IMO renew right now seems like a complete waste of a GCD: Use Flash Heal (or Binding Heal if you're so inclined) instead. It may cost marginally more mana, but has the added benefit of reducing the cooldown of serenity. I see no reason to ever use renew except as a pre-cast buffer.
For the math:
Flash Heal
- 2.8% mana
- 475% upfront
- Reverence: +9%
- Time: 1 GCD cast time
- Baseline: 184 HP%M (healing (throughput in spellpower) per % mana used)
- Baseline: 517 HPC (healing per cast)
Renew
- 2% mana
- 55% upfront, 275% over 15 sec
- Holy Hands: +15%
- Time: 1 GCD cooldown
- Baseline: 189 HP%M
- Baseline: 379 HPC
Deliberately ignored in the equation:
- Any ability that gives a flat healing increase to all abilities
- Artifact overall healing bonus, Follower of the Light, Beacon of Light, intelligence bonus, echo, stats, more spellpower etc
But as you can see - Flash Heal is strictly better in throughput, and only marginally worse in efficiency; and that is assuming absolutely none of the renew ends up in overhealing. Flash Heal can also stack on one target - whereas renew cannot. The only place renew is remotely better is as a healing buffer. And even as such it's fairly worthless compared to just casting Flash Heal.
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Legendaries change this.
Entrancing Trousers of An'juna - Adds two ticks to Renew
Phyrix's Embrace - Hard to model, but promotes multidotting. And has a fun synergy with the doublecast guardian spirit talent in the artifact.
If we focus on the former, two ticks to renew is pretty big. Each tick heals for 55% healing, so that's 110% extra spelllpower per cast of Renew.
Renew
- 2% mana
- 55% upfront, 275% over 15 sec + 110% extra for two more ticks = 440% total healing
- Holy Hands: +15%
- Time: 1 GCD cooldown
- Baseline: 253 HP%M
- Baseline: 506 HPC
As you can see, the efficiency shot through the roof. That's a massive increase to efficiency compared to Flash Heal above. The HPC is now actually comparable to Flash Heal. The main difference is that Flash Heal can be spammed on a single target, whereas Renew cannot. Nonetheless, the legendaries make Renew competitive. I claim it is NOT competitive without it. But maybe I overlooked something important?
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The real interesting part here is the artifact sockets that give bonus traits. I tend to get tons of socketables that increase the power of Flash Heal. I've had 5 stacks of Reverence at some point, which really push Flash Heal way ahead. I've never seen any artifact socket item giving +level to Holy Hands.
- - - Updated - - -
Yeah, I actually forgot Trail of Light in that equation.
This still ain't looking too good for Renew!