Dio is back to the race...that might prove to be a problem then...
Wazzz-suicide bombers are always nice, and the mobile generator almost seems like a requirement in your army, I think both will be a nice addition to what I've seen so far...
Anyway, as another "WIP showing" I will now post basic data about 2 of my heroes (no numbers, just effect)
Lavamancer: (Int) Mystical hero, expert at dealing large amounts of damage.
Rain of Fire-calls down multiple molten rocks from the sky, scattering randomly around, dealing damage and minor confusion on impact, a flame will remain at the impact zone for a few seconds, burning all who touch it.
Overload (Auto)-the lavamancer overloads himself with heat, causing himself to explode, ripping everything nearby apart, however the spell is lethal. (yes, a sapper hero.)
Pyrohemia (Auto?)-causes unit to take damage over time, if dies it bursts into flames that last a while and burn all who touch them.
Soul of the Phoenix (Ulti)-If the lavamancer dies he is restored as a lesser form of himself, if that lesser form survives 30 seconds he is restored into his full power, and is fully healed. (scary with overload, although cooldowns prevents double-blast abuse)
Mistwalker: (AGI) Cunning hero, adapt at causing confusion and avoiding direct confrontation.
Mistform (Auto)-the mistwalker fades into mist whenever it takes damage, temporarily avoiding any further damage.
Shadow Step- teleports anywhere on the battlefield (must have vision, and much more mana/cooldown then blink. used to mount surprise attacks or to fully retreat, not quickly move in and out of combat.)
Shadowstorm- the mistwalker releases streams of black winds that wonder around, damaging nearby enemies.
Calling- summons up to six friendly units from anywhere to the mistwalker (yay instant reinforcements, quite lethal when used properly combined with Shadow Step)
As you see from the first two heroes, the elemental army is more into hit-and-run (or hit and die) and battlefield control then direct confrontation, it does not boast very good melee units, but powerful magics instead. (the 2.5 earth units are the only non-squishy ones...)