((Ok I think everyone has taken their two or three turns. When the Demon hits the 230 foot mark, that's when he hits Fleshbane's attack.
Fleshbane succeeded at getting past Spell Resistance, but the Demon rolled high on his save so he takes half damage (good choice on using Sonic energy here).
Since Menek said as much, he's casting Glitterdust on the Demon, which means that everyone knows where the Demon is at all times. However: This does NOT negate the other benefits of his invisibility. If you attack the Demon then you have a 50% miss chance per attack; roll a d100, and any result between 1 and 50 means you miss.
Also, the Demon is immune to blindness so there's no need to roll the Caster Level check for that.
Menek's Knowledge check tells him that this guy has Spell Resistance, Damage Reduction, True Seeing, and a variety of spell-like abilities up his sleeve - though the check wasn't high enough to ascertain what those abilities are, exactly.))
The demon careens forward with blinding speed; its velocity renders it unable to entirely avoid the area of Fleshbane's sonic attack, but it is able to maneuver around enough to prevent the construct from attacking it on the way by.
Menek's Glitterdust allows the entire party to know where it is at all times - though hitting it still isn't going to be easy.
((Menek's turn is casting Glitterdust; Fleshbane's turn is casting Energy Current. Everyone else may take your turn for the round now. The demon is twenty feet to the side of Fleshbane, and 230 feet away from the rest of the party. The Observatory is about 600 feet behind the party. Sorry if it's difficult to picture but I can't get into Ditzie right now, and plus the distances would be difficult to portray in Ditzie anyway))