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 - $900
Lightly Played - $700
Moderately Played - $600
Heavily Played - $600
Damaged - $500
Near Mint Spanish - $900
Lightly Played Spanish - $700
Moderately Played Spanish - $600
Heavily Played Spanish - $600
Damaged Spanish - $500