Regenerations Restored is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Vanishing 12 (This enchantment enters with twelve time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.) Whenever one or more time counters are removed from this enchantment, scry 1 and you gain 1 life. Then if this enchantment has no time counters on it, exile it. When you do, take an extra turn after this one.