I'll start off with heroes.
How big of a map will this be? 12 player, 10 player? Will teams be even? It has the feel of a Blademasters map to me, but what kinds of heroes are you looking for? Classic AoE, DPS, Support, Healer, Disabler, Buffer, etc, the list goes on. And how do you want to separate each group of heroes? Do you want people to be able to choose which side they go on or are you going to make sure certain heroes remain within each group?
What kind of selection are we looking at? 12 heroes at max? What should be their starting stats and items? Will heroes have access to items early on? Does dying once signal the end of the game for a hero or is there an element of reincarnation outside of Ahkhs?
There seems to be an 4-pronged elemental system set in place, with Death as the outlier. How do you want spells of different elements to interact? Should there be a synergistic effect or no effect at all? Should there be only 4 elements of magic to choose from? (4 and a half if you count Life within Air)
What kind of level cap are we imagining? Level 11? Level 25? How many abilities should each hero (6, I'm guessing) and what level can they be upgraded to? How high should stats go for each hero? I would assume normal stat gains, because you have such high int. modifiers for Xelia's spells?
More questions than ideas, as is my habit, but I want to flesh out the map a little more. xD;