At the beginning of each upkeep, put a strife counter on Crescendo of War. Attacking creatures get +1/+0 for each strife counter on Crescendo of War. Blocking creatures you control get +1/+0 for each strife counter on Crescendo of War.
Near Mint - $0.80
Lightly Played - $0.60
Moderately Played - $0.60
Heavily Played - $0.50
Damaged - $0.40
Near Mint Spanish - $0.80
Lightly Played Spanish - $0.60
Moderately Played Spanish - $0.60
Heavily Played Spanish - $0.50
Damaged Spanish - $0.40