Hi there !
Here are some ideas that just came to me while playing, they are simple and can be improved or changed a lot but I hope you will like them.
Mage -
General idea : Do damage mainly with movement skills.
Passive : +x% damage for movement skills where x is movement speed bonus, gain +20% movement speed, movement skills no longer share cooldown.
Skill idea : “Constellation” - Dash and bounce between enemies, create a detonation at each bounce.
Rogue - Machinist
General idea : Use machine as minion, like decoy and ballista and can also improve shrine buff (duration, effect, get more duration on kill…).
Passive : Your minions do more damage per shrine buff, share your buff with a minion when you invoke it. You are garanty at least one shrine per map.
Skill idea : “Backpack” - Allow you to permanently have a machine on you that auto-attack with less power.
Sentinel - Juggernaut
General idea : A full tank that can dual wield shields but with less damage done. Can summon warrior spirit to attack for him. Spirit usually attack only once before they vanish.
Passive : Allow you to dual wield shield, you do -50% damage and have +100% block effectiveness, you have +200% stun chance.
Skill idea : “Lancier spirit” - A spirit that perform a single dash attack that can bleed enemy and slow them then vanish.
Primalist - Blood Berserker
General idea : A master of bleed ailment that can leech damage based on bleed. Can also reduce ailments and stun effects on himself to prevent him from being stopped.
Passive : +5% chance to bleed on hit per missing %life, +5% bleed damage leech, -1% ailments effects on you for each bleed stack on nearby ennemies and -1s ailments duration for each 10 stacks.
Skill idea : “Blood absorption” - Absorb all the stacks of bleed on enemies in a range. Remove all stacks on enemies and each stack deal 50% of remaining damage. You heal for each stack removed.
Acolyte - Soul collector
General idea : You can no longer regen mana except by killing enemies, and gain damage per current mana.
Passive : No more mana regen, gain +2 mana per kill, gain +% damage per current % mana.
Skill idea : “Soul bomb” - Use all your mana to make an explosion around you that deal increase damage and range per 10 mana spend. You can’t gain mana with soul bomb kills.
Hope you liked those, once again there are just some rough ideas that i tried to make a bit unique for some but I still hope you enjoy to read (and sorry for the english, it’s not my native language).
Thanks for reading !