Via BOLS:
Carnifex - significant cost reduction
Harpy – big overhaul. New model/dual-combo kit, Flying Monstrous, Sonic Screech combines with Vector striking. Additional Spore Mine Cysts may be purchased as upgrades. Default Stranglethorn has new upgrade options.
New Flyer - Fast Attack choice, the alternative build for the Harpy kit.
Ymgarl Genestealers - Special arrival rule is shared with the Lictor, may now purchase standard Genestealer biomorph upgrades.
Hiveguard: new weapon upgrade option (available to a handful of units) that grants skyfire with an "enhanced ability" to ground FMCs.
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Ties in very well to what we had earlier today:
http://40kwarzone.blogspot.com.au/2013/08/rumour-watch-tyranid-harpy-kit.html
Also, check out:
http://natfka.blogspot.com.au/2013/08/tyranids-week-of-information.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+Faeit212+%28Faeit+212%29
Cheers.