Sunburst

Sunburst is a keyword ability designed by Aaron Forsythe that first appeared in Fifth Dawn. The keyword was unpopular in its first outing (partially due to the dissonance with the set's themes) and was somewhat-unsuccessfully remodelled into Converge.

Description
Sunburst appears on both artifacts and artifact creatures that puts charge counters and +1/+1 counters, respectively, on the card when it enters the battlefield. The number of counters is equal to the number of different colors of mana used to cast the spell.

In addition, Sunburst can also be used as a sort of 'X-value'. One card, Arcbound Wanderer has the ability "Modular-Sunburst". "Modular-Sunburst" means that the creature enters the battlefield with a +1/+1 counter on it for each color of mana used to cast it, and when that creature dies, its controller may move the +1/+1 counters onto another artifact creature.

Fifth Dawn's cards with the Sunburst ability all share a visual cue - Mirrodin's five suns somewhere in the art.

Rulings

 * An artifact creature with sunburst enters the battlefield with one +1/+1 counter on it for each color of mana used to pay its cost.
 * A noncreature artifact with sunburst enters the battlefield with one charge counter on it for each color of mana used to pay its cost.
 * The type of counters depends on whether the spell is a creature or a noncreature spell, not whether the permanent that results from that spell will be a creature or a noncreature permanent. Even if March of the Machines from the Mirrodin set is on the battlefield, noncreature artifact spells with sunburst enters the battlefield with charge counters.
 * Sunburst doesn't apply if a card is put directly onto the battlefield from a player's hand. It applies only if it's being casted as a spell.
 * If you pay for a six-mana sunburst creature spell, it enters the battlefield with five +1/+1 counters on it—one for each different color of mana you spent.
 * If you pay for a six-mana noncreature artifact spell with sunburst, it enters the battlefield with three charge counters.