Is this a T2 thread? Ah, never mind. Type Casual then.
There are lots of solutions to Blastoderm. Glacial Wall is the stupidest solution, but it's there. Anything that says "Counter target spell." Is an excellent solution, especially if it's Desertion. Wash Out is great.
It is also essential to Shock, Lightning Bolt, Incinerate or Pyroclasm all creature mana producers that the green mage produces. That way, you have counter power by the time the poor fool gets up to 4 mana.
There's also the Wand of Denial/Bazaar of Wonders approach, but that takes time.
Cheese, counters and a liberal amount of Phoenixes are always good. f you want to go pound-for-pound, there's always Balduvian Hordes. The discard isn't much of a factor if you can draw tons more cards than your opponent.