Spell Damage Increase

(Redirected from SDI)

Spell Damage Increase (SDI) is an item property that increases the damage of most magical attacks that are cast. This property is capped at 25% in PVP provided you dont have more than 30% of a skill in two different spell lines or Animal Taming or Parry. Then, you will become "focused" to that spell line and can display it from your titles menu, under overhead name, skills. So, if you have Imbuing, mysticism and focus you can be a focused mystic, but not if you have mysticism and 31 in evaluating intelligence. It's noteworthy that chivalry is amongst the magical lines even though it has no spell affected by SDI. So, if you have 120 magery and 120 chivalry, you won't be a focused mage. If you are not eligible to be focused, then your SDI pvp cap will be 20%. For PvE there is no cap on spell damage, so pack it on.

There is no formula needed for Spell Damage Increase because it is a true conversion, a 10% increase means your spell damage is increased 10% and so on. The intensity range of the Spell Damage Increase item property is 1% to 18% for found rings and bracelets. The apparent maximum is 50% for special items (e.g., Shattered Obelisk Invasion Spellbook).


As with most code over time, Spell Damage Increase is not as straight-forward as it seems. It does affect Poison Strike and Wither, but it does not affect Pain Spike or Holy Light. It works with Word of Death, as the spell is not dependent on a secondary ability check, e.g. like Pain Spike, which involves Spirit Speak, or Holy Light, which involves Karma.

Calculating Spell Damage

On the other hand factor in resist lowering and additional damage received issues on the target like:

SDI Items













The relative effective %Damage output is in parentheses to set the order.

If the goal is maximum damage, using a slayer spellbook to match your target is clearly the most important element. These are crafted spellbooks with 0 SDI just to make the damage comparison clear. No additional SDI, but slayer books:


Maximum Possible SDI by items

As of September 2017, the maximum Spell Damage Increase from equipment is 160%, which is constituted from the following:

(**A target specific Lesser Slayer Shattered Obelisk Invasion Spellbook 30%, triple damage)


The following resources are required to imbue the highest intensity of Spell Damage Increase (12%):

See Also