All the wearer’s successful melee attacks, ranged attacks, and damage-inflicting spells deal +5 Damage as Eldritch. It does not affect spells which do not deal HP damage. It does not affect scrolls, spells emanating from items, nor spells “cast as a scroll”.
If a spell under the influence of Boots of the Four Winds can affect more than one target, the caster gets a total of 5 extra points of Eldritch damage from the boots,