Common Courtesy

Enchantment, 2UU (4)
Counter any spell unless its caster asks your permission to play that spell. If you refuse permission, Sacrifice Common Courtesy and counter the spell.
"You didn't say the Magic word."
Illus. Mike Raabe

Crystal Keep Rulings Summaries

• This affects all spells, even yours. So you need to ask yourself permission. [QAS 1998/09/09]
• If the player doesn't ask permission, then the spell is countered automatically. [Barclay 1998/08/13]
• If there's more than one in play, you need to ask each player who controls one. [Barclay 1998/08/13]
• All tournament formats have banned cards from Unglued.
• Note - Also see Unglued rulings, Rule 507.

Format Legality	Banned in Vintage, Legacy, Extended, Standard
Printings (1/1)	Unglued (Uncommon)