How to know a bush is warded...?
Just something I've learned over the months as a support: If you are ranged, have auto attack ON, if you stand in a bush, you will attack nearby minions if it is warded.
Dunno if this is common sense in the community, but I still see some who just keep aaing while inside the brush, acting totally stealthy and...stuff.
CLARITY (I told myself to edit, and I did! whee)
Not minion aggro which doesn't work when the waves meet.
Your attack animation will still proc if an enemy can see you via ward/invis. Your projectile when ranged will usually go to a nearby minion, which gives you enough info to back off.