[WaifuApple]

If you want to give it a drawback of a different kind, I could also suggest that the range of a Talis is specifically made long. Consider this, being unable to place it within 1-3 tiles of yourself. You can relocate it past 3 range to it's normal end point, but once it's out cannot retract it back in (or make THIS cost 3M, and moving it around otherwise still 1M)

This gives them that long range superiority but forces blind spots on the mage that will cost them to patch up, allowing melee attackers to bring the fight to them without the mage being able to easily switch gears from artillery to close range. If they want to stay close to the talis to keep their blind spots safe, this results in them reducing the effective range they get from the Talis in the first place.