Whenever a player casts a spell without asking your permission while casting it, counter that spell.
When a player asks you permission to cast a spell and you refuse, counter that spell and sacrifice Common Courtesy.
Near Mint - $0.80
Near Mint Non-English - $0.80
Lightly Played - $0.70
Lightly Played Non-English - $0.70
Played - $0.60
Played Non-English - $0.60
Heavily Played - $0.50
Heavily Played Non-English - $0.50
Damaged - $0.40
Damaged Non-English - $0.40