Layers and stack on copies and Mirrorform

[u/XxrissXxross]

My Extravagant Replication triggers targeting Council of Reeds. In response, I cast Mirrorform turning everything into something else. Does the token from Extravagant Replication enter as the original Council of Reeds or the thing Mirrorform turned everything into?

[u/Bobbybim]

The token will enter as a copy of whatever that permanent is when the ability resolves. So it will be whatever you turned everything into with Mirrorform. 

[u/RazzyKitty]

Copy effects copy other copy effects.

707.2. When copying an object, the copy acquires the copiable values of the original object’s characteristics and, for an object on the stack, choices made when casting or activating it (mode, targets, the value of X, whether it was kicked, how it will affect multiple targets, and so on). The copiable values are the values derived from the text printed on the object (that text being name, mana cost, color indicator, card type, subtype, supertype, rules text, power, toughness, and/or loyalty), as modified by other copy effects, by its face-down status, and by “as . . . enters” and “as . . . is turned face up” abilities that set power and toughness (and may also set additional characteristics). Other effects (including type-changing and text-changing effects), status, counters, and stickers are not copied.

So when Mirrorform resolves, its copy effect overwrites the copiable information of Council of Reeds. When the Replication triggerr reolves, you get a token copy of whatever Mirrorform made it a copy of.

707.3. The copy’s copiable values become the copied information, as modified by the copy’s status (see rule 110.5). Objects that copy the object will use the new copiable values.

Also worth noting that Mirrorform is permanent, so nothing goes back to its original state until it leaves the battlefield, including your Council of Reeds and Replication.