Grey Spells
Grey Magic to me seemed like sort of a catch-all category where the designers put whatever they couldn’t fit in the other schools of magic. I think that is why it was so overpowered.  I have tried to remedy this by concentrating on the fluff idea that Grey Magic is generated by winds and storms. So, I have kept the movement spells, but tried to give the school more focus which has the side effect of getting rid of the most over powered spells like Traitor of Tarn and Dance of Despair.

Bridge of Shadows  is remained Ride the Wind and troops are transported by a magic wind (obviously) but the spell is otherwise unchanged. Note that warmachines cannot be moved, nor can enemy troops.
Stormcall and The Dark Steed remain the same.

Grey Wings - Power 1, Range 12”/36”
 The wizards summons the clouds and mists which meld together to form a pair of wings for the target model, who must be within 12” on the caster. The model may immediately move up 36” in any direction. If moved into HtH combat, the model counts as charging in the next round. Note that the model so moved must be a single figure, so a character on a steed could be moved, a warmachine, character in a chariot, on a monster mount, could not.

Voice of Thunder - Power 2, Range 24” (replaces Horn of Andar)
 The caster voices a cry which booms like thunder across the battle field. All enemy units within range (obviously including characters who are counted as seperate units for the test) must roll equal to or under their Tou on a d6, a 6 always fails, or be stunned by the sound and unable to act in their next turn.

Shield of the Wind - Power 1, Range 36” (replaces Radiance of Ptolos)
 The target unit is surrounded by buffeting winds. Any missile fire (including that from warmachines) from or at the unit is deflected by the winds and rendered harmless. Further, any fliers attempting to combat the unit will require 6s to hit on the first round. After one round of HtH, the Shield of Wind is dispelled. Remains in play.

Speed of the Storm - Power 3, Range 12” (replaces Traitor of Tarn but only because they are both Power 3)
 Strong winds swirl about the unit bearing them quickly across the field. The unit is granted a Mv of 12 by the spell. The unit therefore marches and charges 24” and rolls 3d6 for pursuit or fleeing. (This spell may seem overpowered, but before everyone blasts me as a power gaming munchkin, remember that it is expensive, and the enemy will get two chances to dispel before the spell will have any effect except perhaps from breaking or fleeing). Remains in Play

Call the Winds - Power 2, Range 24” (replaces Dance of Despair)
 The wizards summons the powerful winds of a storm and directs them at one unit. The unit is immediately pushed d6+3” directly away from the wizard. A unit pushed off a table edge, will return in its next movement phase, but cannot move further that turn. Whenever the unit attempts to move, roll a d6. If the result is less than the unit’s strength (for mounted units, use the mounts strength, otherwise use the strength score of the greatest number of models, usually rank and file troops), its movement is unaffected. If the result is equal to or greater than the unit’s strength, its movement is reduced by d6” (like a reverse Jaguar standard). Flying creatures are unable to fly high regardless of the results of the strength test. Remains in Play.

The Balance - Power 2, Range 12” (replaces Crown of Taidron)
 Known for their wisdom, Grey mages often act as judges within the Empire. Often this means overseeing trials by combat. They know that while Sigmar favours the brave, he is often too busy to intervene and so might conquers right. The Grey mages use this spell to ensure that does not occur. Choose any two models in BtB contact. The mage may then nominate up to three characteristics. These characters are then averaged (rounding up) between the two models. For example, an Empire hero and a Vampire Lord (who is armed with the blade of leaping bronze) are in BtB contact. A Grey Mage friendly to the hero successfully casts The Balance and chooses Str, Int, and Attacks, the Hero has str 4, int 5, at 3, the Vampire has str 7, int 8?, at 6 (4+2),  so the averages are str 6 (5.5), int 7 (6.5), and at 5 (4.5) and each model is assumed to have these characteristics until the spell is dispelled. Note that magic items that enchance characteristics are counted in the averages and have no other effect when the magic is in play.  Remains in play.

Hail Storm - Power 3, Range 30” (replaces Pit of Tarnus)
 Dark and chill clouds gather over the target unit. At the wizard’s command, they unlease a fercious downpour of hail-stones. The unit takes 3d6 str 4 hits with normal armour saves. The hail obscures vision and makes the ground treacherous, so the unit can move at only half speed for the next turn.