Wither

Wither is a keyword ability introduced in Shadowmoor. It was also featured in Eventide.

Description
Damage dealt to a creature by a source with wither isn't marked on that creature. Rather, it causes that many -1/-1 counters to be put on that creature.

Wither is primary in black and red, and secondary in green.

Wither was considered and rejected for Amonkhet.

Rulings

 * Wither's effect applies to any damage, not just combat damage.
 * The -1/-1 counters remain on the creature indefinitely. They won't be removed if the creature regenerates or the turn ends.
 * Since damage from a source with wither is real damage, it follows all the other rules for damage. It can be prevented or redirected. When it's dealt, it will cause lifelink and other similar abilities to trigger.
 * If the source of the damage is still on the battlefield at the time that damage is dealt, its characteristics are checked to see if it has wither. If the source has left the battlefield by then, its last known information is used.
 * Damage from sources with wither affects players and planeswalkers normally.

Cards that grant Wither
Creatures Enchantments Artifacts
 * Corrosive Mentor (black creatures you control)
 * Fists of the Demigod (as long as enchanted creature is black)
 * Blight Sickle - Equipment

Plane card that grants Wither

 * Raven's Run (all creatures)

Trivia

 * Wither was featured as rules card 6 of 6 in the Shadowmoor set and 6 of 8 in the Eventide set.