Day of the fallen

When Day of Fallen enters the battlefield, it
creates x 8/8 black balrog creatures with flying,
which remain under your control for x turns.
As soon as balrog creatures summoned this way
are removed from the battlefield, at the end of x
turns, target player searches their library for a
legendary card, reveals it, and puts it on top of
their library
The Balrogs fought during the Nirnaeth Arnoediad,
where Gothmog led the invasion.