Iroas, God of Victory prevents any damage done to itself or other creatures you control while giving them all menace
That's a pretty solid worst-case scenario
For 4 mana you fill your own graveyard and draw the card your opponent chooses, but they dont usually have a good choice either way
Then if that isnt enough, Stonehoof goes all super Brawn by giving your other attacking creature you control those same two abilities, turning your entire army into a damage-dealing with near-complete impunity
On the other hand, counterfeit cards are designed to be as realistic as possible to fool people into thinking they are real, so while all counterfeit cards are technically proxies, not all proxies are counterfeit cards
For example, when mill was turned into a keyword, not only did new cards use it, but every existing card that moved cards from the library to graveyard received updated oracle text