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 - £1.20
Lightly Played - £1.00
Moderately Played - £0.90
Heavily Played - £0.60
Damaged - £0.40
Near Mint Non English - £1.20
Lightly Played Non English - £1.00
Moderately Played Non English - £0.90
Heavily Played Non English - £0.60
Damaged Non English - £0.40