As an additional cost to cast Fire Covenant, pay X life.
Fire Covenant deals X damage divided as you choose among any number of target creatures.
9/16/2007 If X is 0, the number of targets must also be 0. If X is greater than 0, the number of targets must be at least 1 and at most X. You must distribute at least 1 damage to each target.
9/16/2007 You divide the damage as you cast the spell. You can't redistribute the damage if any of the target creatures becomes illegal before the spell resolves.