The pacer test

When this card enters the battlefield put a -1/-1 counter on all creatures your opponent controls.
At the start of an opponent's upkeep, each of their creatures get a -1/-1 counter unless that creature
would be destroyed from it.
The FitnessGram Pacer Test is a multistage aerobic capacity test that progressively gets more difficult as it continues. The 20 meter pacer test will begin in 30 seconds. Line up at the start. The running speed starts slowly, but gets faster each minute after you hear t