Serra's Hymn
Urza's Saga — uncommon
Enchantment
Serra's Hymn rulings:
2004-10-04: You count the number of counters, then divide up the prevention during the announcement of the ability. Each targeted creature receives the appropriate amount of damage prevention when the ability resolves.
2004-10-04: You can activate the ability (choosing no targets) even if there are no verse counters on it. It doesn’t do anything useful if you do this.
2004-10-04: Adding a counter is optional. If you forget to add one during your upkeep, you cannot back up and add one later.