2018-04-27 : Aim counters are interchangeable. Your Haphazard Bombardment can destroy any permanent you don’t control with an aim counter on it no matter how that counter got there—for example, those aim counters may have come from a second Haphazard Bombardment that you or another opponent cast.

2018-04-27 : If one or more of the permanents with aim counters on them have indestructible, select the permanent destroyed at random from among the permanents with aim counters that don’t have indestructible.

2018-04-27 : Players can’t take actions between the time the permanent is randomly selected and the time it’s destroyed. Notably, if a land is randomly selected, it can’t be tapped for mana before being destroyed.

2018-04-27 : The nonenchantment permanents that receive aim counters aren’t targeted. Permanents with hexproof can be given an aim counter this way.