+2% Gild damage per level. The damage added late game by this ancient is crucial to reaching the late game floors. As gilds increase from the mere 50% increase to upwards of 1000%+ per gild, the damage quickly piles on to help you forge onward. With many gilds in one unit the damage one level in this ancient is roughly +4% per level for that unit (e.g. 100 gilds in unit is 5000% basic damage, then one level in Argaiv boosts 5000/5200 of the whole units' damage).