Some abilities completely replace the resolution of another effect or game step. These abilities are referred to as “Replacement Effects” and can be identified by use of the word “instead.” A replacement effect specifies what part of an effect or game step it is replacing. When that effect (or part of an effect) or game step would occur, it does not occur and the replacement effect happens in its place.
If a replacement effect causes something that is tagged for destruction to not be destroyed, this replacement effect does not resolve until the card would be put into the discard pile. When the card would be put into the discard pile, instead of putting the card into the discard pile, remove the destroyed tag and complete the instructions of the destruction replacement effect.
If no effect is specified by the replacement effect, it refers to another part of the same effect the replacement effect is a part of.
Example: Aaron plays Dimension Door, and then reaps with a creature. Normally Aaron would gain 1 Æmber from reaping with the creature. However, the Dimension Door has set up a replacement effect that replaces the gaining of an Æmber from reaping with stealing an Æmber, so Aaron steals 1 instead.
Example: Katherine has a Commander Remiel with an Armageddon Cloak attached to it, and her opponent plays Gateway to Dis, destroying each creature in play. The destroyed effect given to Remiel by the Armageddon Cloak is a replacement effect that is replacing the destruction of the creature. This destruction is being replaced with healing the creature fully and destroying the Armageddon Cloak instead. This causes the destroyed tag to be removed from Commander Remiel and be given to the Armageddon Cloak.
Example: Jamie plays Ronnie Wristclocks while her opponent has 7 Æmber. Normally, Ronnie Wristclocks’s play effect steals 1 Æmber from her opponent, but since Jamie’s opponent has 7 or more Æmber, the replacement effect kicks in and replaces stealing 1 Æmber with stealing 2 Æmber instead.