This project is using updated version of DrDamage originaly by Gagorian. He abandoned the project 12 years ago. Since then I felt that this addon has great features for any dps or healer as it provides each skill of ours with detailed description on it's stats and provide suggestions of how much each point invested in new stat will affect the output. That's why I updated the code.

MrDamage displays the calculated damage or healing of abilities with talents, gear and buffs included on your actionbar buttons. The addon also adds various statistics to the tooltips in your spellbook and on the actionbar.

Slash Commands:

/mrd or /mrdmg or /mrdamage

Functionality:

Supports all classes
Actionbar addons supported: Default, Bartender 4, CT_BarMod, Dominos, elvUI, Macaroon, Nurfed AB, IPopBar, nUI, ReAction Bars and RDX.
Places text with the metric of your choosing on the actionbar buttons.
Damage and healing statistics are placed into your tooltips. This includes for example critical hit chance, spell damage and damage coefficients, averages, DPS, DPSC (damage per seconds cast), damage until OOM and more!
Your own buffs and your target's debuffs are taken into account.
Allows manual modification of the essential talents, buffs and character stats used to calculate. For example you can test how much increasing your spellpower by 100 would increase your damage or healing output.
If you're overwhelmed by the amount of statistics presented, you can use the options reduce the amount to whatever you feel is important!

Acronym/abbreviation list:

AP = Attack Power
RAP = Ranged Attack Power
SP = Spell Power
Ht = Hit rating
Cr = Critical strike rating
Exp = Expertise rating
Ha = Haste rating
Ma = Mastery rating
HPS/DPS = Healing/Damage Per Second
HPSC/DPSC = Healing/Damage Per Seconds Casted
HPSCD/DPSCD = Healing/Damage Per Seconds CoolDown
HOOM/DOOM = Healing/Damage (until) Out of Mana
HPM/DPM = Healing/Damage Per Mana
DPE = Damage Per Energy
DPF = Damage Per Focus
DPR = Damage Per Rage
DPRP = Damage Per Runic Power
MPS = Mana Per Second (How much mana the spell uses per seconds casted)
GCD = Global CoolDown