What does the spell damage effect? Normal caster nukes (would assume yes on this)? Normal caster dots? Normal caster aas? Bard dots? Bard nuke song? Bard nuke aas (boastful bellows)? Weapon procs? Swam pet procs (not even sure if any have this)? Normal pet procs? What does the Heal amount effect? HoT you cast on others? Direct Heals cast on others? Bard regen song? Lifetap procs? What about Clairvoyance? Do bards get back mana for insult songs from this?
From a SD perspective, it is very minimal the benefit it provides back. Having said that, if everything is equal, someone with more SD is going to parse higher than someone with a lower SD. It won't be a large amount, but it will be something that makes one finish first and one behind. And I say that with the assumption that everything else is equal. Same class, same gear, same spells cast, same ADPS at same time, and every spell is a max critical hit. Of course, that last one brings in variance... hence why I said all things equal.
There's 3 values that the spell damage stat can take for DDs. Add together the nuke's cast time and its recast time, we'll call that the total_cast_time. If total_cast_time is greater than 7.0 seconds then: bonus_damage = floor((total_cast_time / 7.0) * spell_damage) If total_cast_time is greater than 2.5 seconds but less than or equal to 7.0 seconds then: bonus_damage = floor(0.167 * (total_cast_time - 1.0) * spell_damage) If total_cast_time is less than or equal to 2.5 seconds then: bonus_damage = floor(0.25 * spell_damage) At least, that seems accurate for every spell I've tested it against. The bonus damage is added pre-crit, meaning if the nuke crits then the bonus damage will be multiplied by your crit multiplier.
