"The walls of Argive were built by a peaceful dynastic union that has guarded us against war for fifteen centuries. The lesson is clear."

Baird, Steward of Argive

Vigilance
Creatures can't attack you or planeswalkers you control unless their controller pays {1} for each of those creatures.

Bloomburrow Commander

Commander Masters

The List

Dominaria

Vigilance
Creatures can't attack you or a planeswalker you control unless their controller pays {1} for each of those creatures.

Dominaria Promos

In a Two-Headed Giant game, creatures can attack your teammate and planeswalkers your teammate controls without requiring a mana payment. This is a change from previous rules.

If you control Baird, your opponents can choose not to pay to attack with a creature that attacks "if able." If there's no other player, planeswalker, or battle to attack, that creature simply doesn't attack.