Second Chance

Enchantment

At the beginning of your upkeep, if you have 5 or less life, sacrifice Second Chance and take an extra turn after this one.

2004-10-04:
It is not optional.
2004-10-04:
The ability will only trigger if you have 5 or less life at the beginning of upkeep. This is checked again at the start of resolution and nothing happens if you do not still have 5 or less life.
2004-10-04:
If multiple “extra turn” effects resolve in the same turn, take them in the reverse of the order that the effects resolved.
2010-06-15:
On resolution of the trigger you have to sacrifice this card if you have 5 life or less. If you can’t (because it is not on the battlefield, for example), then you still take an extra turn after this one.