“ADD A RANDOM legendary card to your hand” even might be allowed. “Discover” the desirable legendary card is too overpowered.
It’s also excessive that using the same legendary card twice or many times by copying (maybe by returning the battlecry legend too) .
nah
it has to be discover is more flexible and sometimes the legendary isnt the best option at the time
Do I detect a level of “SALT” in this post? or is it just me?: 
I only partly agree with you, I think it’s okay to discover legendaries and copy them, however, there should be a limit of 1.
But honestly, Legendaries are not often copied numerous times for it to really matter. It’s more of a Wild thing than anything else.
Discover cards must NOT be able to find other cards with discover. This is the problem to solve.