Migración vs Power Drain

Una duda que surgió el domingo: Si el oponente juega nuestra querida Interstellar Migration y lo interrumpimos con un Power Drain.¿Dónde va la migración? ¿Al descarte o al fondo del mazo?
========== Hastur ==========
Power Drain
-----------
Type : Event
Cost : 2
Subtype : Spell.
Game Text : Disrupt: Cancel an Action or Response just played or used.
Flavor text :
Illustrator : Kyri Koniotou
Collector's Info : Core Set F100
========== Yog-Sothoth ==========
Interstellar Migration
----------------------
Type : Event
Cost : 2
Subtype : Yithian.
Game Text : Action: Choose a Yithian character and return it to its owner's hand. Action: Put Interstellar Migration on the bottom of your deck to choose a deck. Discard X cards from that deck. X is equal to the number of Yithian cards in your discard pile. This effect can only be triggered from your discard pile.
Flavor text :
Illustrator : Paul Carrick
Collector's Info : The Key and The Gate F37
========== Hastur ==========
Power Drain
-----------
Type : Event
Cost : 2
Subtype : Spell.
Game Text : Disrupt: Cancel an Action or Response just played or used.
Flavor text :
Illustrator : Kyri Koniotou
Collector's Info : Core Set F100
========== Yog-Sothoth ==========
Interstellar Migration
----------------------
Type : Event
Cost : 2
Subtype : Yithian.
Game Text : Action: Choose a Yithian character and return it to its owner's hand. Action: Put Interstellar Migration on the bottom of your deck to choose a deck. Discard X cards from that deck. X is equal to the number of Yithian cards in your discard pile. This effect can only be triggered from your discard pile.
Flavor text :
Illustrator : Paul Carrick
Collector's Info : The Key and The Gate F37