Khaefneset, Hand of Erathis

At the beginning of combat, put an assassinate
counter on target creature an opponent controls.
Whenever a creature with an assassinate counter
blocks or is blocked by Khaefneset, Khaefneset
gains first strike and deathtouch until the end
of turn.
At the beginning of each end step if 3 or more
creatures died this turn transform Khaefneset.