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 - $2.25
Lightly Played - $2.25
Moderately Played - $2.00
Heavily Played - $1.50
Damaged - $1.25
Near Mint Non-English - $2.25
Lightly Played Non-English - $2.25
Moderately Played Non-English - $2.00
Heavily Played Non-English - $1.50
Damaged Non-English - $1.25