Iron Will

With Iron Will, 100 Strength grants 50% increased Spell damage through the Keystone but no longer grants Strength's inherent 200 maximum Life. The increase applies to Spell damage, not Attacks merely because the character has Strength. Iron Will currently comes from Irongrasp rather than the passive tree, and the same body armour also grants Iron Grip.

Strength no longer grants its inherent Life

The line Gain no inherent bonus from Strength removes Strength's ordinary +2 maximum Life per point. Explicit item, passive, or Skill effects based on Strength remain separate unless their wording also depends on the inherent bonus.

Two Strength grants 1% increased Spell damage

The Keystone grants 1% increased Spell damage per 2 Strength. At 100 Strength the resulting modifier is 50% increased Spell damage.

The Skill must deal Spell damage

The modifier applies to damage dealt by Spells. It does not turn Attack damage into Spell damage and does not make a Skill a Spell.

The damage is Increased

The Strength-derived value joins the applicable Increased and Reduced Spell damage pool. It is not a separate More multiplier.

It is not on the current passive tree

Iron Will is a valid current Keystone effect, but the official 0.5.2 passive tree contains no Iron Will node. Irongrasp grants the effect directly.