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 - $3.00
Lightly Played - $2.70
Played - $2.10
Heavily Played - $1.80
Damaged - $1.50
Near Mint Non-English - $3.00
Lightly Played Non-English - $2.70
Played Non-English - $2.10
Heavily Played Non-English - $1.80
Damaged Non-English - $1.50