Small expansion
From MTG Salvation Wiki
A small expansion is a set of Magic: The Gathering cards that contains less than 250 cards and builds on the themes, story, and mechanics for the block named after it. This set is the second or third of its block and includes no basic lands.
New mechanics may be introduced; mechanics from the preceding large expansion may be expanded upon. As an example, the set Torment is a small expansion in the Odyssey Block. It continued the Odyssey keyword mechanics of flashback and threshold and introduced madness.
