Nope, this is not a joke 
The card has three uses which probably need more thorough explanation:
- Most obviously, it’s a Wanderer counter. A pretty narrow and punishing one for sure (hence the name), but note that it only refers to decks and not action bars. So, at 6 mana when this minion comes down the Wanderer player will still have some cards left to try and close the game out with. In a game where cards like Crossbones and Night Watcher exist, I don’t think this is anything too narrow design-wise.
- It promotes consistent deck-building (your random one-off cards are no longer safe!). The inconsistency has been one of the more complained features of Wanderer.
- Most importantly, you can build your own deck around it by playing mostly one-offs and three-offs of whatever you’d like to combo with in the late game. The effect is like Quaresma, but more powerful in the right hands, hence the much lower statline. You still need to handle your replaces carefully, since if you play for example play two cards with the same name before Inferos hits the board the last copy will be lost forever (and same if you have all other copies in your action bar).
And last, if anyone’s wondering, prismatics and non-prismatics don’t matter (Inferos counts all cards with the same name as the same card).
