Corruption

Corruption is the magenta bar to the lower right of the UI, split into 4 segments, each representing one point of corruption.

Corruption is generated whenever you deal damage to enemies, or passively over time with the Corruptive pommel

Using your special attack, which requires at least one full corruption point, consumes all your corruption, refilling one Spellblade charge and dealing extra Damage per full corruption point consumed. Any partial points are also consumed (and wasted), resetting your corruption to zero.