Spell power is an attribute that effects the gear of mages, usually their weapon and weapon soul. It has nothing to do with the spells you craft yourself. It’s generally considered the most important attribute for a mage.
Mage weapons generally do base damage (like all weapons) then have an ability like healing, resurrection, or extra damage that happens “once in a while” or a similar trigger. To get a decent amount of healing or to resurrect with any reasonable amount of health, your mage needs Spell Power.
Spell Power also adds a bonus to Base Weapon Damage, as explained in the Damage page. However, base weapon damage is not important for mages; abilities are what matters for mages.
Your mage’s Spell Power is the sum of it’s base attribute from their fighter training level and all the bonuses from all their gear and gems. Your Hero will also add to the Spell Power you see for the fighter as well as dynamically increase Spell Power during battle.
If you have resurrection mages who are resurrecting your fighters with not enough health, or your healers are not performing well, then that means the mage needs more Spell Power.
Calculating Spell Power
Example #1
Here below you see one of my mages equipped with a standard healing scepter. Notice her Spell Power is 57612.
If we look closer at the weapon, we see that “once in a while” it will restore 8842 (+63211 of the spell power) health to an ally. The 8842 is constant and will always be the same. The more interesting number is the 63211. This number is the mage’s total spell power (57612) times the weapons “spell power multiplier”.
We can calculate the weapon’s spell power multiplier, if we want to. Although it’s not that useful to know it exactly. Just seeing if it’s higher or lower than another weapon is probably all you need.
Spell Power Bonus (63211) = Mage’s Spell Power (57612) * Weapon’s Spell Power Multiplier
Or to put it another way…
Weapon Spell Power Multiplier = Spell Power bonus / mage’s spell power attribute
So in this example: 63211 / 57612 = 1.097
Example #2
Lets look at another weapon on the same mage. Below is the Underwater Oracle Staff from the Pirate Treasure Event (January 2021). Because this item has lots of Spell Power, the mage’s Spell Power attribute is now 63147.
This is an event weapon with more abilities, but the primary ability is healing. It does “10000 (+25663 of the spell power)”. The constant here is higher, 10000 compared to 8842 in the other example. However the second number (25663) is lower despite the mage having more spell power now. This tells us that this weapon has a lower Spell Power Multiplier. Lets calculate the spell power multiplier to see how much lower…
Spell Power Multiplier = Spell Power bonus / mage’s spell power attribute
Spell Power Multiplier = 25663 / 63147
Spell Power Multiplier = 0.4064
What can we learn from this?
If I’m going to use the second (event) weapon, then I will need to load it with Spell Power to compensate for the lower spell power multiplier. My reward for doing so will be all the extra abilities that the event weapon has, which are even better with a rune added.