Dragonblade
Adventurer
Oooooh, a Summoner class could be very cool in 4e. Takes me back to playing Final Fantasy on my SNES. 
It would be easy to balance too given the new one monster = one PC paradigm. Under the assumption that the summoner would be a controller, it would be cool to summon soldier monsters and stuff to fight for you. And summon little elementals and stuff to carry stuff or do tasks for you.

It would be easy to balance too given the new one monster = one PC paradigm. Under the assumption that the summoner would be a controller, it would be cool to summon soldier monsters and stuff to fight for you. And summon little elementals and stuff to carry stuff or do tasks for you.