From the Warhammer Chronicles 2004, the Revised Lores of Magic are listed as "Trial Rules" but are considered "Unofficial, but Highly Recommended" by the Design Team.
In the cities of Men, the Lore of the Heavens is called Astromancy. It is the magic of the sky and stars, of portents, fate and the movement of heavenly bodies.
This spell can be cast by a Wizard and gives the player a chance of re-rolling dice during the remainder of his own turn.
If successfully cast, roll a D3 to determine the number of re-rolls the player can make. Each re-roll entitles the player to take any single D6 dice (including one of the dice rolled on a 2D6, 3D6, etc) he has rolled and roll it again. Any dice can be re-rolled but the player cannot re-roll a re-rolled dice... he only gets one chance to overcome a duff roll! Any re-rolls not used by the end of the turn are wasted.
This spell can be cast on a friendly unit that is within 12" and which is engaged in close combat.
If successfully cast, all subsequent dice rolls of a 1 made either to hit or to wound by this unit can be re-rolled that turn. Re-rolled scores of 1 stand - you cannot re-roll a re-rolled dice.
This spell can be cast on any unengaged enemy unit within 24" of the caster. If successfully cast, the unit is struck by lightning causing D6 Strength 4 hits. These hits are distributed exactly like hits from shooting.
This spell can be cast on any unengaged enemy unit within 24" of the caster. If successfully cast, the unit is struck by a thunder bolt causing D6 Strength 4 hits with no Armour save possible. These hits are distributed exactly like hits from shooting.
This spell can be cast on all enemy units which are visible to and within 12" of the caster. If successfully cast, all enemy units within range and sight are affected. Each unit takes D6 Strength 4 hits, distributed exactly like shooting.
This spell can be cast upon any fixed point on the tabletop. If successfully cast, place a suitable marker over the exact spot affected - a small coin is ideal for this.
Once cast, the player rolls a D6 at the start of each player's turn (ie, at the start of his turn and at the start of his opponent's turn). On a score of 1-3 nothing happens, but place another marker on the first. On the score of a 4-6 the spot is struck by a comet. All units from either side which are within D6" multiplied by the number of markers already placed are struck by the comet. Each unit struck by the comet takes 2D6 Strength 4 hits. For example - if there are two markers in place and the D6 roll is a 4, all units within 4 x 2 = 8" are struck. The Comet is not aspell as such, although the spell can be dispelled while in play, (remove all markers), and a Wizard cannot have more than one Comet in play at one time.