MTG Keyword Rules — Comprehensive Rules Glossary

Sunburst 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. Example: The ability “Modular—Sunburst” means “This permanent enters with a +1/+1 counter on it for each color of mana spent to cast it” and “When this permanent is put into a graveyard from the battlefield, you may put a +1/+1 counter on target artifact creature for each +1/+1 counter on this permanent.”

If an object has multiple instances of sunburst, each one works separately.