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 - $1.000
Lightly Played - $800
Moderately Played - $700
Heavily Played - $600
Damaged - $500
Near Mint Spanish - $1.000
Lightly Played Spanish - $800
Moderately Played Spanish - $700
Heavily Played Spanish - $600
Damaged Spanish - $500