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 - $1.30
Lightly Played - $1.00
Moderately Played - $0.90
Heavily Played - $0.80
Damaged - $0.70
Near Mint Spanish - $1.30
Lightly Played Spanish - $1.00
Moderately Played Spanish - $0.90
Heavily Played Spanish - $0.80
Damaged Spanish - $0.70