Spark Fiend (51)

When this creature enters, roll two six-sided dice. If you rolled 2, 3, or 12, sacrifice this creature. If you rolled 7 or 11, don't roll dice for this creature during any of your following upkeeps. If you rolled any other total, note that total.
At the beginning of your upkeep, roll two six-sided dice. If you rolled 7, sacrifice this creature. If you roll the noted total, don't roll dice for this creature during any of your following upkeeps. Otherwise, do nothing.