Force Bubble | Magic: The Gathering
Formats Force Bubble is Legal in
Official Oracle Text for Force Bubble
When there are four or more depletion counters on Force Bubble, sacrifice it.
At the beginning of each end step, remove all depletion counters from Force Bubble.
Official Rulings for Force Bubble
10/4/2004 : If you take 6 damage at once, it will replace all 6 damage and put 6 counters on it. Then the second ability will trigger. Any additional damage you take before this ability resolves also results in counters, but once the ability resolves, this card is sacrificed.
10/4/2004 : The effect does not prevent damage, it replaces it so the damage is neither dealt or prevented.