The Whisperer in Darkness

Deathtouch, Menace
Whenever a nontoken creature you control deals
combat damage to a player, that player mills the
top card of their library.
Whenever a player mills or discards a card, put a Madness counter on The Whisperer in Darkness.
At the beginning of your upkeep, if The
Whisperer in Darkness has seven or more
Madness counters, transform the Whisperer in Darkness.