Vira, Twilight's Shadow

Whenever Vira, Twilight's Shadow takes damage, put a twilight counter on Vira, Twilight's Shadow.
When Vira, Twilight's Shadow dies, destroy X target creatures and put that many 2/2 black Shadow Spirit creature tokens into play under your control, where X is equal to the number of twilight counters on Vira, Twilight's Shadow