I like your idea, but don't you think consecutive summon will tilt off the class balance? I mean sure it's nice but you don't want the server just filled with one certain classes. besides, consecutive summon will burn your mana/MP quickly, and that will be bad for the long run. And instead of sacrifice summon, why dont we just make ultimate summon with items that you can buy in NPC? that way the money circulation(this is good for long run) will keep in the line and keep one class not to become super OP like one certain game that was managed by PLAY**** INTERACTIVE. But, I like most of your idea, especially the support type summon, it reminds me of Rising Force Online.