Analysis, Obsolete, Spells and Talents
Note: As the Tree of Life aura was subsequently increased to a 6% bonus, this post is no longer relevant.
As briefly mentioned and discussed in my previous post, Blue: Changes to Buffs and Debuffs, a significant change is being made to the way that Tree of Life aura will function in Wrath of the Lich King. It will no longer afford benefit based on the Druid’s total Spirit but instead will function in the same was as a Paladin’s Improved Devotion Aura, providing a flat 3% increased healing to the raid. Although it was stated that the values listed were considered maximally-talented, it remains unclear whether 3/3 Improved Tree of Life will be required to meet the 3% bonus or whether it will afford an additional .45% bonus. Either way, this change will affect all spells based on their +Healing coefficient (or their corresponding spell power coefficients).
The TBC Tree of Life aura was a flat +Healing bonus that scaled with Spirit. It’s value decreased as +Healing increased, assuming Spirit stayed constant. Assuming they increased at the same rate, the value stayed the same. The WotLK aura is a multiplicative bonus that will instead scale with +Healing.
To help better explain the significance of this change, let’s consider two spells called DirectHealage and Hawtness. At your current +healing, DirectHealage derives 25% of its total amount healed from +Healing while Hawtness derives 75%. If you were to boost your +Healing by 8%, DirectHealage would get a 25%*8% = 2% total boost. Hawtness, on the other hand, would get a 75%*8%=6% total boost. With the new aura, both spells would simply get 3%.
This means that spells with high coefficients (Lifebloom, Chain Heal) will be nerfed by this change while spells with lower coefficients (Nourish, Regrowth) will be buffed. We can use the following formula to determine how much Spirit would be required under the current Tree of Life aura (25% of Spirit converted to +Healing) to match the new aura’s bonus:
Spirit = 4 *(((+Healing * +Healing coefficient) + base healed) * aura bonus) / +Healing coefficient
By applying this formula to the 3% and possibly 3.45% auras and using numbers previously determined in Direct Heals in Wrath, we can graph these values of Spirit at increasing values of +Healing.
Assuming you have somewhere in the neighborhood of 600 Spirit and 2000 +Healing at the conclusion of TBC, this change represents a nerf to triple-stacked Lifebloom and Chain Heal – two spells with the highest +Healing coefficients – and a buff to both Nourish and Regrowth. Although the base amount healed is also a determining factor, you can generally expect heals with higher coefficients to have been reduced in effectiveness by this change while those with lower coefficients to have been increased.