(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)

When Invasion of Azgol enters the battlefield, target player sacrifices a creature or planeswalker and loses 1
life.

//

Ashen Reaper

Menace

At the beginning of your end step, put a +1/+1 counter on Ashen Reaper if a permanent was put into a graveyard from the battlefield this turn.

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When this Siege enters, target player sacrifices a creature or planeswalker of their choice and loses 1 life.

Menace
At the beginning of your end step, put a +1/+1 counter on this creature if a permanent was put into a graveyard from the battlefield this turn.