This card’s effect is not activated when equipped to an opponent’s “Relinquished” or “Thousand-Eyes Restrict”.
If your opponent uses “Change of Heart” on a face-down “Ameba” and Flip Summons it, when it returns to you during the End Phase, its effect activates and you take 2000 damage.
Netrep Rulings:
The effect of “Ameba” does not activate when control of “Ameba” changes while “Ameba” is face-down.