Rule · Chapter 1
cr:1.14.4
An effect-cost is a cost that requires payment in the form of generating one or more effects. To pay an effect-cost, the player must be able to successfully generate and resolve the specified costs.
Example: Hope Merchant’s Hood has the text “Instant – Destroy this: Shuffle any number of cards from your hand into your deck, then draw that many cards,” which is an activated ability with an effect-cost of destroying Hope Merchant’s Hood.