[Micah]

More expensive and incurable just raises the luck factor of what chassis types you end up with and what afflictions they come with. Tarts are a needed end game balance mechanism to unlock magic paths for certain nations and shouldn't be constrained too tightly. Adding in other summons is a much better idea IMO, as it increases strategic chassis selections as opposed to increasing the importance of luck. There are also a reasonable amount of counters available to tarts IMO.