Hearthpwn

So ive been tinkering with this deck myself and have a 90% similar line up, question on why the assassinates? they are very heavy 5 mana is a killer when we have vilespines. Same with the fan of knives,  for draw? The shiv and fans we dont have spellpower to benefit from so they are heavy mana low damage cards. Whats your thoughts on spiritsinger umbra for the swarmers, Perhaps ill swap out one assass for umbra and and another for barnes barnes would be great for swarmer and aya, plus that could generate more targets for shadowstep, barnes in aya shadow step her ! Just pinging around some ideas, overall great deck