Abhorrent Shambler

You may only cast Abhorrent Shambler if a creature you don't control has a stress counter.
Abhorrent Shambler enters the battlefield tapped.
When Abhorrent Shambler enters the battlefield or attacks, target opponent loses 1 life, then create a 3/2, colorless Tentacle creature token.
"Behold the infinite malignity of the stars!"
— the Ancestor