War Tuba's

War Tuba's enters the battlefield with 7 advancement counters on it.
{1}: Put an advancement counter on War Tuba's. Activate only as a sorcery and once per turn.
{t}: Roll a d20. If your roll is less than the amount of advancement counters on War Tuba's, blocking creatures you control gain first strike until end of turn.
With good hearing and trigonometry, these large aircraft detection devices could give you the location and altitude of an approching aircraft.