Allow Cassiopeia's damage amp to proc with auto's

Instead of Twin Fang needing to be cast twice to fully amp the poison damage from Q and W, they should make it amplified with damage from auto-attacks, as well. Twin Fang's mana is expensive and this will help her mana management better.

Why did they nerf her mana costs again in the first place? She still has some of the worst CC in the game.