Phasing is a mechanic that comes in two different forms: a keyword ability, and a keyword action called phasing out
You can find two, one, or (if you really want) none
The actual writing for the editing text was done by Del Laugel, Magic 's lead editor
If you are able to attack a battle (with Sieges, every player who is not the protector can do so, though this may differ with other battle subtypes), you can attack with your creatures , or use direct-damage spells that allow you to either target a battle specifically, or merely say any target
If Jenova isn't on the battlefield at the time its first ability resolves, use Jenova's power as it last existed on the battlefield to determine how many counters to put on the target creature