Pastoral Field

{t}: Add {w} to your mana pool
{w}{w}{t}: Prevent all damage from combat
this turn. Place 5 time counters on Pastoral Field.
You may play this as an instant.
As long as there are any time counters on Pastoral Field, no one may attack.
During your upkeep, remove one time counter.
If Pastoral Field has no time counters, exile it.