First off the answer to this question I think is No but I can not find it in the BRB.

Daemonettes 30 (10x3) are a big 16" away from a building. ( front edge of building is on the same line of the front rank of the unit).

Part 1, So the unit does a quick reform and point in the direction of the building ALL in a big long line ( 30 models all back to back , Daemonettes ;)) . Front rank move towards the building by 10" , second rank go the opposite direction 10" and third rank go up 2" to fill in the space.

Part 2, Next they move towards the building 6" and touch it.

Part 3, Can they ALL enter the building , remembering that the 18 of models are over double the movement stat away . One is infact 30" away from the building.

Enjoy.

Isn't there a rule against individual models moving beyond their Movement Value when performing reforms - specifically instated to prevent obviously ugly/gamey moves such as the one you describe?

I mean: Personally I would never attempt this, because.. meh.. But I would hope that there's actually a RAW-instance that also prevents you from doing it. :)

Part 1 and part 2, I do not think there's a problem . Unless the quick reform movement of the model and the move of 6" are added together. Which I do not think is the case.

Its the extra movement by the Conga line that appears altogether wrong , In order to get the model into the building.
If you add up all the movement in that single movement phase , the min is going to be 16" ( 10" quick reform + 6" move to touch building) and the biggest movement for one of the models will be 46" ( 10" + 6" + 30" ) .

Are you sure a model with M6 is allowed to be 'displaced' (i.e. move within the formation of the unit) by 10"??

That's what I was getting at. I have some vague 'memory' gnawing at the back of my head that I've seen/heard of such a restriction.

That would mean that you couldn't actually reform a Horde of Daemonettes into a 30" long conga line is one go, of course.

If I'm right the movement after you've reformed isn't part of the equation:

1 - You reform any way you like without any individual model in the unit moving more than its basic M-value.

2 - You may move the unit up to its basic M-value.

No?

Reform = Centre of unit, double movement allowance max.
Quick Reform= Reform + base movement.

So M6 is 12" displacement.

It is legal RAW but is a lame rules loophole.

Oh, Rulebook updates and they haven't changed this yet.
Surely we are missing something!!

(I have not played in big tournments but buildings must be/can be a real nightmare!)