SunburstSunburst is a static ability that functions as an object is entering the battlefield. “Sunburst” means “If this object is entering as a creature, ignoring any type-changing effects that would affect it, it enters with a +1/+1 counter on it for each color of mana spent to cast it. Otherwise, it enters with a charge counter on it for each color of mana spent to cast it.”
Sunburst adds counters only if the object with sunburst is entering the battlefield from the stack as a resolving spell and only if one or more colored mana was spent on its costs, including additional or alternative costs.
Sunburst can also be used to set a variable number for another ability. If the keyword is used in this way, it doesn’t matter whether the ability is on a creature spell or on a noncreature spell.
If an object has multiple instances of sunburst, each one works separately. (CR 702.44) (This artifact enters with a charge
counterTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) on it for each color of mana spent to
castTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) it.)
At the beginning of your upkeep, you may gain life equal to the number of charge
countersTo counter a spell or ability is to cancel it: remove it from the stack without resolving it. A counter on an object or player is instead a marker that changes characteristics or interacts with rules or abilities; for example, a +1/+1 counter modifies a creature’s power and toughness. (CR 701.6; 122.1) on this artifact.