In addition to being horrible in round 3, Vyper is a dead card against many decks, such as scoiatel, SY, most NR decks.
And even Skellige doesn't suffer that much. If you play this card against lippy, in blue coin, you have a good chance, losing on equal cards, just to force the lippy to be played sooner.
And lippy is not even tier 1, against PF, the only thing this card does is to force the opponent to play Hjalmar, or harald earlier.
Even the Cahir, which is a card, which some consider that should be nerfed, is not widely used because it is very situational, for a 9 provision card. Vyper is extremely more situational than Cahir.