Baird, Steward of Argive
Legendary Creature — Human Soldier
Vigilance
Creatures can't attack you or planeswalkers you control unless their controller pays 
for each of those creatures.
"The walls of Argive were built by a peaceful dynastic union that has guarded us against war for fifteen centuries. The lesson is clear."
Christine Choi
Commander Masters (CMM)
• #15Rulings
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.
(wotc • 2023-07-28)
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.
(wotc • 2018-04-27)
Rulings
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.
(wotc • 2023-07-28)
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.
(wotc • 2018-04-27)