The Swamp of Sadness

At the beginning of your upkeep, sacrifice
The Swamp of Sadness unless you
sacrifice a creature.
{t}: Add {b}{b}{b}{b}
"Fight against the Sadness, Artax. Please,
you’re letting the Sadness of the Swamps
get to you. You have to try. You have to care.
For me. You’re my friend. I love you."
— Atreyu, The Neverending Story