It means they cant be countered - and if you also find a way to flicker your enchantments to ensure they can enter the battlefield without being cast at all, you suddenly have a way to put nearly everything in your deck into play with ease
This might be due to a spell or ability resolving, a permanent you control entering the battlefield with counters, or combat damage from a source with toxic, infect, or wither
But what about cards that are printed by a third party
It becomes a creature again if its not attached.) Reach, trample This permanent enters with X +1/+1 counters on it
A Snapshot card lives in a magnetic case, on a shelf, in a collection binder, or in someone's hands
If that front face can't be put onto the battlefield, it doesn't enter the battlefield