Radiance

Radiance is an ability word associated with the Boros Legion of Ravnica. Radiance means "Effect on target [something] that affects all [somethings] that share a color with it." Radiance was introduced in Ravnica and is only on red or white cards as those are the color of the Boros Legion.

Rulings

• All radiance spells have a single target (usually a creature). The spell affects that creature and each other creature that shares a color with it.
• If a radiance spell targets a black-green creature, it will affect black creatures, green creatures, black-green creatures, blue-black creatures, green-white creatures, and so on, as they each share at least one color with the target.
• Oftentimes creatures on both sides of the table will be affected by a single radiance spell.
• Only one creature is targeted. If that creature leaves play or otherwise becomes an illegal target, the entire spell is countered. No other creatures are affected.