Test of the Gom Jabbar

Each player puts a vow counter on a creature
they control and sacrifices the rest. Each of
those creatures can't attack you or planeswalkers you control for as long as it has
a vow counter on it.

"Like sifting sand through a screen.We sift people. If you were unable to control your impulses, like an animal -- we could not let you live. You inherit too much power."
- Reverend Mother Gaius Mohiam