Instant SP2 Killmonger vs Sunspot, how?

I just fought Killmonger using Sunspot in Arena and Killmonger instantly got full SP2 on the power meter, how does this happen?

Comments

He purifies debuffs and gains power

While his armor active, each debuff on him give him amount % of power. Your incinerate made him unlimited powerrr. Read his ability

He gains power when debuffed