Drawback

A drawback is a limitation or an additional adverse effect on a card to prevent it from being too powerful. A spell can do thing X but only under a certain condition or to a certain subset of cards.

For example, no cards are allowed to be strictly better than basic lands. As such, Urborg, Tomb of Yawgmoth would be strictly better than a basic Swamp but suffers from the drawback of being legendary with which there can be no two copies of it on the battlefield at the same time, rendering additional drawn copies of Urborg, Tomb of Yawgmoth useless.