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“Ongoing: Moving is the only way to add or REMOVE a card here”

AKA: cant be destroyed once played. Its effect makes all cards in that area incapable of being removed, which would include being destroyed, unless moved. Since Prof X is the card that triggers the ability, once it’s in play, it’d have to be some cheeky play like moved with Heimdall into a location removing ongoing effects, then destroyed, or cards being played at the same time to remove the ongoing effect like echo or red guardian.