Request to support the Early Frost talent for Mages:

• must glow button of Frostbolt
• must glow as combat-only counter, limited to having the talent
• must glow on special cooldown determined by last time of start cast

The talent works as follows:

• starting to cast Frostbolt puts it on internal cooldown
• spell can still be cast during this special cooldown, but not empowered with faster cast time
• once 15 secs have elapsed since last start cast, the cooldown ends and spell gets empowered again

The important point is that START_CAST is the one and only important event. It doesn't matter if the mage stopped casting, got interrupted, or if the spell missed. As long as the cast was at least started, it goes on special cooldown.

Note: due to server lag issues, and because the game client already glow this button, it may not be relevant to implement this feature.