Scout Bombing is an effective way to thin out enemy numbers before your spear hits... problem is that if the player is online, you can kiss your 100,000 scouts goodbye.
Heres what you do.
Lets say your target is 15 minutes archers march.
Set a camp time on your scout bomb to arrive in 16-17 minutes. Note the time of arrival of your bomb, then set up your Spear with layers and remember to delete the camp time. Now watch the clock in the bottom right corner of the march screen and when it ticks down to the arrival time of your scout bomb, wait 1 more second, then march.
Your enemy sees them both, sees when they both arrive, but what does he do?
1) Close the gates and kill all your scouts, but loose all his ATs... sure, most evony players dont keep archer defenders (pikemen, swordsmen walls) in their city, you should hope for this, then send in a full regiment of cavalry to decimate his archers.
2) Open the gates and not only loose his ATs but also all his archers easily since your scout bombs weeded them out.
Either way, he is fucked!