So Time would be the fourth member of the astral schools. Since time is part of the universe it is an astral school. Here's my idea for how it would work: Time is the most powerful weapon in the Spiral. Wizards who can posses the power of time can literally bend time into their favor. However, the ability to utilize Time magic requires great power... And great patience.
So essentially Time is made up of charms, wards, and several other utility-like spells. The difference is Time spells give HUGE boosts (for example, blades that give +40-100% damage boost depending on levels) but there is a catch. Since Time is so hard to control it costs great amounts of energy (pips) to control it. So huge boosts, huge pip cost. Also since it based on time, these spells have countdown rounds, meaning once casted, you have to wait a certain amount of rounds before it activates.
Here's my ideas. If anyone has any other suggestions for Time Magic, please reply