Channel

Channel is an ability word indicating that a card may be discarded for an effect. It was introduced in Saviors of Kamigawa.

Channel was featured only on spirit creatures, and designed to have resonance with the spirit's abilities. Flavorwise, Channel represents spirits gathering all of their energy and using it for a one-time special effect. It has an interaction with Epic and Soulshift; Channel abilities are often similar to real spells, but you may play them after playing an Epic spell. Soulshift allows you to reuse Channeled cards.

Due to the generic cost and unrestrained effect, it has similarities in many future mechanics. Transmute turned spells into tutors; the Evoke ability from Lorwyn has a similar flavor and use; Reinforce turned cards into +1/+1 counters; Bloodrush turned creatures into combat tricks. Channel was later considered for Throne of Eldraine, which developed into Adventures.

Rulings

 * Channel cards have an activated ability that lets you discard them to get a temporary effect that's similar to the creature's normal ability.
 * The ability after "channel" is an activated ability that you can play any time the channel card is in your hand and you have priority.