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 - $0.95
Lightly Played - $0.90
Moderately Played - $0.71
Heavily Played - $0.57
Damaged - $0.38
Near Mint Non-English - $0.95
Lightly Played Non-English - $0.90
Moderately Played Non-English - $0.71
Heavily Played Non-English - $0.57
Damaged Non-English - $0.38