This is a huge model. A massive marine transport that hopefully Forgeworld will have coming soon.
There are a several more images of this over on Heresy 30k (where these came from), so go check them out.
via Loken at Heresy 30k, images from Raglan
http://apocalypse40k.blogspot.com/2015/11/forge-world-mastadon-work-in-progress.html
The Mastadon is coming from Forge World!
The giant troop transport we have heard about will be coming from Forge World. These are some early WIP shots. Word is the top has been re-designed.
Thanks to Raglan on the Horus Heresy Forum for posting these.
Loken
These are some earlier images from back in July
http://heresy30k.invisionzone.com/index.php?/gallery/image/5013-mastadon/