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.
NM-Mint - $1.90
Lightly Played - $1.70
Moderately Played - $1.50
Heavily Played - $1.30
Damaged - $1.00
NM-Mint Non English - $1.90
Lightly Played Non English - $1.70
Moderately Played Non English - $1.50
Heavily Played Non English - $1.30
Damaged Non English - $1.00