Kurogiri was given the Warp Gate Quirk, which allows him to produce dark fog from his head and hands.

Source: https://www.cbr.com/mha-quirks-can-beat-all-might/

The heroes' situation has never been so dire, and the chain of terrible events that Kurogiri had triggered seemed to have decided the war once and for all, until the dust settled a bit.

Source: https://www.cbr.com/my-hero-academia-manga-chapter-377-final-battle-descends-into-chaos-but-theres-a-twist/

The manga has teased several times that Shirakumo's personality has somehow survived inside Kurogiri.

Source: https://screenrant.com/kurogiri-shirakumo-my-hero-academia-villain-changes-sides/