i'm not sure if this still open for suggestions but here goes.
Elemental class that summon a clones of him self with different gears.
Flame : uses hammer with shield and hammer smash on ground dealing fire dmg to all enemies AOE.
Electric : dual wielding DPS clone that uses shock dmg as he rampage on his target Single target high DPS.
Ice : a mage that use staff and specialist in crowd control skills like Hailstorm for stun and freezes.
as you increase the tier of these clone summoners they learn more deadly skills you can arrange the skills they learn to balance it not to be too OP.
as for passives each clone have his own passive skills such as the Flame clone learning more Block chance on his shield. ice mage get more chance to freeze and stuns, dual wielder heal you for percent of the dmg he deals. and other passives for your clones.
couple passives for your self such as upon being hit your Fire spirit explode within sending all enemies around you knockback. while ice spirit bring you a ice shield to protect you from dmg for the next 5 sec. chances and times you work on those C:
you have 2 portal skills one that port you away when it gets dangerous like phase. and another phase but that teleport your clones to wherever you desire them to be like teleport them in middle of crowd or front of boss.
as for charge bar we have lot of passive increase charge bars now we need something like Berserker and Embermage. when your charge bar gets full spirit of elements get summons floating above your hit shooting rampage of all elements at your enemies such as burn, freez, poison, and shocks. idk if i'm going too far with this guy C: but just bored and giving it a go idk you may like some ideas.
at tier 3 of each clone will have a chance when he die he summon a way stronger version of him for the next 10 sec.
its not necessarily to have all 3 summons, you can work your self to be 3rd roll you work on the Flame tanker and DPS while you be the crowd control char, or you be the tanker while having DPS and Crowd control mage helping you and so on.
further more information. you can have the Flame hammer clone to have a skill similar to Berserker howl that make all enemies in range forced to target him. well i don't wanna go too far i'm not sure if even most of the stuffs i said even possible so even if these doesn't work i hope you can have some good ideas from these things to add to your current elemental plan.