Okay, so you're taking 4 and the Knights die.
Tap the Vale to play Cadaverous Knight. Done.
Spiderman: 14
Hand: 5
Deck: 28
In Play: Lotus Vale (T: add 3 mana of any color)(T), Island, Mt, Horrible Hordes (2/2, Rampage 1)(T), Cloud Elemental (2/3, flying, can only block flyers)(T), Cadaverous...