A very good druid spreadsheet is at
http://elitistjerks.com/attachments/f73 ... tables.xlsAdditive healing terms:
Genesis 5/5 = 5% to HoT portions of spells and also Tranquility. Does not apply to direct-heal portion of Lifebloom or Regrowth.
Gift of Nature 5/5 = 10% to all healing.
Improved Rejuvenation = 15% to Rejuvenation.
Glyph of Healing Touch = minus 50% to healing touch.
I believe 20% from Glyph of Regrowth is additive (top of my head), but verify in spreadsheet.
Multiplicative terms (multiplied with each other, and the sum of the additive terms)
Tree of Life Aura: 6%
Master Shapeshifter: 4%
Empowered Rejuvenation: 5/5 adds 20% to your SP for all spells that have a HoT component (including the non-HoT portion of Lifebloom and Regrowth). Idols that add SP to a single spell (PvP idols and some older PvE idols) do not benefit from Empowered Rejuventation.
Empowered Touch: 2/2 Adds 40%/20% to the spell coefficients of Healing Touch and Nourish, so the Nourish coefficient goes from .671 to .871 with ET.
The 20% bonus to Nourish with a HoT is additive with Glyph of Nourish (6%/HoT) and with 4t7 (5%/HoT), but multiplicative with Gift of Nature.
The "all spells haste" portion of Gift of the Earth Mother is 10% spell haste at 5/5 (multiplied with other haste effects). The lifebloom portion is 10% reduced GCD (corresponds to about 11% haste).
I believe most mana reduction% are multiplicative (9% from Moonglow, up to 10% from Tranquil Spirit, 20% to HoTs from Tree of Life, something from 2t7). Subtractive reductions (such as Idol of Awakening) occur before the % reductions.
Our clearcasting proc, Omen of Clarity, is usually modeled as either a 6% or 3.5/60 per cast. It also procs from melee (used on General) at 3.5 ppm, based on weapon speed.
The mana refund when lifebloom blooms is not reduced by items (or clearcasting) that reduce the initial mana cost.
I'm probably missing something, but with spell tooltips and coefficients, that should just about cover the math for Druid heals.
Edit: 2t10 effectively increases the base heal of Wild Growth by 42%, but does not change the spellpower coefficient.