The main drawback of using the Mangekyou Sharingan is, that with frequent use, the user's eyes go blind and lose their power. In contrast to the Izanagi or the Izanami, this doesn't happen instantly.

Although it seemed that Kakashi had suddenly awakened the Mangekyo Sharingan in Shippuden, the reality is actually far from it. Since Kakashi’s Sharingan bears a link to Obito, the two awakened ...