Move silently doesn't matter if you fly, right? Not sure about that though.
And Glitterdust assumse the dragon gets to do anything. It might not even know the guy's coming in. Just get a scrolls of Divine insight to pump your Hide and Move silently up by 15 and the dragon will have even harder a time to punch through Darkstalker.
Edit: These challenges remind me of a dispeller played until a few weeks ago: Level 16, 17 Contingencies (Celerity was banned, but our party Psion helped me to get Anticipatory strikes against Disjunction and whatnot), saves between 32 and 48 and +5 against all spells, permanent See invisibility and Arcane sight, Persistent True seeing, saw in all kinds of darkness, 120' blindsight, 100 feet Mindsight, Greater Mirror image on at all times, Mind blank, Greater Blink, movement actived Etherealness (yes, Haures...), around 300 hit points, initiative of +23 and AC in the 60's. I refused to die.