DoT Spells and Multi-Hit Spells counter Illaoi
Illaoi's spirit duration is reduced by 1 second every time she is damaged by an enemy champion. I played against an Urgot as Illaoi, he put his DoT on me, and the spirit I pulled from him was gone in about 2 seconds because it reduced the duration for every 0.25 tick of the DoT. Same with Miss Fortune's Make It Rain ability.