also, try to wait on casting antimatter (AM)...
theres a queue you need to be aware of in the creature slot
[ 7 ] [ 3 ] [ 5 ] [ 1 ] [ 4 ] [ 2 ] [ 6 ] <-- middle row
at least wait until he cast the 3rd creature to cast your first AM, and dragon > shrieker like Nume said
the second and consequent AM should follow the first one, dont immediately cast them until he accumulate a couple more creatures
the main goal of AM is to negate his damage output
its not rocket science so once you get the hang of things, its easier to know when to play your AMs or when to hold on to them