Legions is the only expansion in Magic to be 100% creature cards. This was done to help amplify the creature-based mechanics of the block. While there were quality cards, Limited play was stale. The set also features the return of the fan favorite creature type, the Slivers.

The following mechanics first appeared in Legions:

• Amplify - As a creature with Amplify came into play, its controller could reveal creature cards from their hand that shared a type with it to add +1/+1 counters. Creatures with Amplify were generally costly.
• Provoke - Based on a card from Stronghold, when a creature with provoke attacked, it could untap an opponent's creature and force that creature to block it.
• Double Strike - A mechanic suggested by a fan during the Magic Website's You Make the Card Promo and was officially turned into a mechanic. A creature with Double Strike would deal both First Strike and regular combat damage.
• Morph Triggered Abilities - Some creatures had an ability that would trigger upon turning face up.
  

Story: Kamahl and the Cabal, in their uneasy alliance, set out to defeat the threat of Akroma. Ixidor was killed, but Akroma continues her mission to destroy Phage. Meanwhile, the slivers (last spotted in Tempest and its era) have been reintroduced as clones of the originals. In a final battle, Phage and Akroma merge into one being, Karona, the false god.