A lot like the Lich King himself, a mix of both Frost and Shadow allows this character to summon different spirits through his touch with the afterlife. As if to be a mix of a shadow priest, frost made and warlock, the Medium has abilities to damage via frost or shadow and also specialize with his/her spirits.
Dark SpecThis spec allows the Medium to focus in his DoT spells and take on an affliction warlock type of role. Type of spells would be:
Spirit Touch - Spirits from beyond the grave afflict the target with
x damage over
y seconds. Target is also dazed for 3 seconds after cast.
Haunted - The caster places a curse on the target, making the target at risk of being attacked by spirits. Every 5 seconds the target recieves
x damage from surrounding spirits.
Cold SpecThis spec gives direct damage often with a chill effect from the spells cast. Type of spells would be:
Chilled Breeze - The target is afflicted by a cold breeze hitting for
x damage and slowing movement speed by 50%. Does not stack with other movement imparing effects.
Spirit Shard - The caster hurls a spirit shard at the target, causing
x damage and knocking the target to the floor. This effect does break current casting by the target.
Spirits SpecThis spec is similar to the warlocks demonology spec, allowing the Medium to summon extra spirits and increase their powers. Allows increases buffs the Medium uses. Type of spells would be:
Feed From Spirit - *Buff* Allows the caster to recieve
x mana per second from its spirits health. Lasts 10 seconds or until pet dies.
Summon Unsettled Spirit - Summons an Unsettled Spirit in the control of the Medium. This is a DPS Spirit much like the Felguard, yet in the look of a spirit. Control many abilities to attack and has a 2 second stun.
Summon Peaceful Spirit - Summons a Peaceful Spirit in the control of the Medium. This is a more of a support spirit, preffered for it's buff to both the Medium and his party. Does a weak amount of dps but has a small health regeneration ability.
The class would be available to Trolls, Undead, Humans and Night Elves, all races who are generally in touch with both or either the shadows or spirits.
Another idea is like a shadow priest, the Medium can take on a Spirit Form. While unable to deal as much damage directly, it's armour and resistances are increased and movement speed is also increased. This would be specced in from the Dark tree.
Summonable SpiritsPeaceful Spirit -
http://wow.allakhazam.com/images/mobs/unfettered_spirit.jpgUnsettled Spirit -
http://wow.allakhazam.com/images/mobs/TormentedSpirit.jpg