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.
Legalities
tlrnot legal
duellegal
brawlnot legal
pennynot legal
PreDHnot legal
Rulings · 3
wotc
Each player, including you, must put a vow counter on a creature they control if able. They can't choose to opt out and sacrifice all of their creatures. The creature you put a vow counter on will remember its promise if another player gains control of it.
wotc
If the vow counter is moved to another creature, it won't prevent the second creature from attacking normally.
wotc
If the vow counter is removed from the creature, it can attack as normal.
Notes
No price observations yet — this card is in the canonical catalog but a refresh hasn't seen a market price.