Eee! Thanks! And sure thing.
Invocations
Least
- Beguiling Presence (+6 to Bluff, Diplomacy, and Intimidate)
- Dark One's Luck (+5 luck bonus to any one save)
- See the Unseen (See Invis + Darkvision 60')
- Eldritch Spear (Blast range 250')
Lesser
- Charm (Charm Monster, Will DC 19, only 1 victim at a time)
- Fell Flight (fly speed = ground speed)
- Walk Unseen (Invisibility w/24 hr duration)
- Flee the Scene (55' dim door, leaves Major Image of caster)
Greater
- Devour Magic (+8 melee touch, +12 caster level)
In combat, Sigil's basically a "gunship." Primary tactic is to hover out of melee engagement range, and use long range blasts. She does 8d6 a shot (using an item that increases its power), and has Precise Shot so she can safely snipe into melee. Thrice a day she can Empower the blast.
Noncombat, Sigil is a sneak; using invisibility, flight, and short range teleports to get places she's not supposed to be, and to do so without attracting notice. Devour Magic is useful mainly for getting rid of negative effects on party members, or temporarily nullifying magic traps (spotted with her constant Detect Magic). Charm is what she uses if someone DOES notice her. It's quieter than killing.
Sigil also has very high Bluff (+22), Intimidate (+22), and Use Magic Device (+21), as well as a small arsenal of scrolls including Nondetection for when Invis REALLY needs to work.

With her Mask of Disguise (same as a Hat) she can infiltrate with a Disguise of +21 (+23 when using Bluff to act).
Assuming no magic item use, she has no area attacks, and is a bit vulnerable to SR. Also, if her Flight is dispelled, she's got very few options for melee combat beyond getting OUT of it. Her AC is respectable...27 if she uses her wand of Shield. She also has the Communicator feat, for Arcane Mark, Message, and Comprehend Languages, each once per day.
Basically, Sigil is designed as a magical troubleshooter, with a spread of powers that give her a variety of options, rather than a tight focus. Future invocations will probably be used to increase her offensive options with things like Vitriolic Blast and Eldritch Chain or Cone.