Google is no help! Plugin to prevent DMG while flying?

Ok my players have 2 ways to fly.
Either use /fly (in survival) and other is Creative mode (with limitedcreative)
I have blocked all damage in limitedcreative creative mode from players BUT how i can prevent all damage if player is in creative and uses /fly?

People are flying above a mob trap and beating mobs from air so they get free xp and loot (i try to prevent this) and mobs cannot hit back. Any plugin to prevent this from happening? I tried google, no help!

 

I'm pretty sure there is no plugin for this the best thing to do would e to remove their permissions for fly and just give them creative.

 

I dont want to :E.. Donors have access to /fly... Obviously the only way is to do so though.

 

You could always request that a plugin be made in the plugin request section.