[MasterNuke]

Barbarians: Berserk - Toggle skill that increase damage and speed at cost of defense/resistances.
Warriors: Guard - Toggle skill that increases defense and enables shield blocking at cost of speed.
Thief: Combo - Damage increase that scales with multiple hits in a time frame. Basicly, the more you hit an opponent within a time frame, the more damage you deal with successive hits. It would favor smaller, faster weapons.
Alchemist: Throw - Ability to throw bombs to deal explosive damage(maybe different kinds of bombs ex. ice bomb, shock charge, sticky bomb) and throw supportive potions on allies.
Sorcerer: Spell Mastery - Passive bonuses to cast speeds and efficiency. Access to attune spells and can cast without wands.

Attune Spells - Spells available to only sorcerers that are attuned to the spell's tree.

Examples:

Comet(missile attune) - The already existing comet spell.
Icewave(cold attune) - Point blank area effect spell from the caster that hits all within moderate range with cold damage. Very short cast time.
Fireball Volley(fire attune) - With no target, shoots lots of fireballs in all directions. With a target, shoots several targeted fireballs at the target. Moderate cast time.