Akhra: Mechanics

Flashback: You may cast this card from your graveyard for its flashback cost. Then exile it. Used on 4 cards: Card72933, CB09, CB12, CB14

(5C) [Returning Mechanic]

Convoke: Your creatures can help cast those spells. Each creature you tap while casting an artifact spell pays for 1 or one mana of that creature's color. Used on 0 cards:

(5C) [Returning Mechanic]

Swarm: When you cast this spell, put a 1/1 colorless insect token named Scarab with Pestilence onto the battlefield for each spell cast before this on this turn. Used on 3 cards: Flickerstorm Mirage, Coleopteran Matriarch, Matriarch's Pageantry

(B/U/G) - basically storm but specifically for these creature tokens.

Decay: At the beginning of your upkeep, put a -1/-1 counter on this permanent. Used on 12 cards: Foreshadowing Mirage, CU09, CB02, UB03, CR08, Shala, Mirage Merchant, CB04, Ghastly Augurist, Flickerstorm Mirage, Unsettling Mirage, Soothing Mirage, Visceral Mirage

(Blue/Black/Red)

Pestilence: {t}

, Sacrifice this creature: distribute up to X -1/-1 counters to target creature you don't control, where X is this creature's power. Used on 1 cards: Soulstealer Scarab

(Black/Green)

Bloom: Used on 14 cards: Torn Allegiance, CR02, CR01, (Pocket Sand), UU02, Imperious Rejection, UB05, CU03, CW03, CR09, Card73086, Card73822, Champion of Anfertiri, Card73915

"If a land has been played this turn."

(5C) This mechanic makes players care about whether the first land this turn had been played. It's a mechanic designed to build player skill.

In card text or details pages, write the mechanic's code name (playtest name) between square brackets, like "[Crittercast]", "[Bushido 1]" or "[Delay 4 {2}{R}{R}]". It will be expanded to the mechanic's name plus reminder text, such as "Suspend 4 – {2} {r} {r} . (Rather than cast this spell from your hand,...)"
To expand a mechanic's name but not its reminder text, include parentheses at the end of the square brackets: "[Crittercast()]", "[Delay 9 {R}()]".