Please remember that these are rumors.
via 4Chan
Crawling Plague (named Venomthrope), Finecast
- Like the other named tyranids is taken as a brood upgrade.
- Three rows of vents on its back, tail is much longer and coils itself around a piece of scenery. Mouth tendrils are shorter and spread open around its mouth like it's trying to spit out something, with liquid dripping out of it.
- Torrent weapon, AP- Poison 4+. Gimmick is on a 3+ place a marker anywhere on where you placed the template. Following turn place the small end of the flamer template on the marker and aim it in any direction, roll again on 4+ every subsequent turn to see if it stays on the field.
- Grants stealth to all models within 6" and shrouding to itself. Venomthropes create 5+ cover, so they synergize.
- It Lurks in the Mists: Special deployment gimmick instead of deploying on the board, at the start of any movement phase except the first you can deploy the Crawling Plague within 6" of any venomthrope.
- Mutation from the new Hive Fleet Karkinos, which is specialized in toxic weaponry and the usage of venomthropes.
Tyranid Prime, plastic clamshell
- Larger Warrior, head crest has four prongs, additional shoulder plates that interlock down over part of the chest, armor in general is sharper and extends farther out with a slight upward curve. Looks like you could impale a guardsman on its back.
- On foot, devourer and scything talons, dead easy to switch out components with Warriors and Raveners.
- Details of the fluff are quite a bit different. The Prime is designed as a perfect hunter, created to fit any battlefield and seek out and eliminate enemy commanders while supported by evolved broods in this regard.
- Apex Brood: The Prime can take a single retinue of "Apex" Warriors, Raveners or Shrikes. They receive T/WS/BS +1 and the Prime auto passes LOS! rolls while attached to the Apex Brood. Somewhat more expensive than their normal counterparts (+5 to +10 pt each depending on the creature)
- No more +1WS/BS when attached to regular warriors, that's replaced by the retinue.
- Hunter-Killer: Enemy characters cannot refuse challenges from the Prime.
Older stuff from the same source on 4chan
Army-wide notes
- No FOC and ally table changes
- Devastation and Adaptation are new power tables with 3 powers each + primaris.
- Primaris for Devastation = Warp Blast, Adaptation = Onslaught (similar to battle-focus)
- All Tyranid powers can be used with either one or two charges to increase the effect.
- Ravenous Advance: Units with this rule can run & assault in the same turn.
- The Ground Trembles: All MC cause d3 Hammer of Wrath hits.
- Red Terror, Deathleaper and Old One Eye are unique upgrades to their respective broods.
Mycetic Spore/Mycetic Hive Node, plastic dual kit
- Spore is a Dedicated Transport, notable changes are that SC can join and MC broods can all opt to get spores.
- Hive Nodes are bought by HQ models (1-3 choice for Tyrants, 1 for every other HQ), no transport capacity.
- Nodes provide Synapse and can be configured in one of many ways. Grants poison or shrouding to nearby units or terraforms (Dangerous Terrain) the surroundings.
Harpy/Erinye, plastic dual kit.
- Harpy is designed to kill infantry hordes/provide support via its special vector strike.
- Vector striking it can either use Spore Mine Cyst to create blasts along the path or Sonic Screech to halve initiative and cause a pinning test.
- Erinye is an AA variant in Elite, very different front torso/head piece with gribbly tentacles.
- Increased Swoop speed and its gimmick is grappling other flyers.
- Vector strike -> dice roll 4+ -> the enemy flyer is dragged directly behind where the Erinye ended its move, including a new facing.
- Both can buy broods of Gargoyles that can drop off in the movement phase when not vector striking.
Zoanthrope (Doom)/Genethrope, plastic dual kit.
- Zoanthropes are ML1 psykers, have access to the Devastation, Telepathy, Telekinesis tables.
- Genethropes are similar, but have access to the Adaptation and Biomancy tables.
- New unique biomorphs. Increased Shadow in the Warp range, Deny the Witch boost aura, two others.
- Both types can upgrade up to ML2 but only ever get 1 power, each Elite choice is a unit of 1-3 that can contain mixded Zoan and Gene.
- Doom has access to all the above tables and comes with Essence Leech and 3 powers.
- Consumes a wound every time it uses a power (except for Leech), but can keep casting until a Perils roll or its down to 1 wound.
Carnifex
- Old unused bimorphs in the box are options again.
- Base cost the same but upgrades are much, much cheaper overall but lots of "only buy 1 out of this list" kind of choices which greatly limits what a fex can have.
- Tusked gives HoW an AP value, Thornback increases the number of HoW hits.
- Enhanced Senses gives Night Fighting.
- Tail Scythe & Tail Mace each deliver a single hit to all models in BtB at Ini 1, with different stats.
- Living Battering Ram rule: Changed to allow the Carnifex to assault the contents of a building/transport on a 4+ if it was destroyed by its charge, rolled once for the brood.
Whatever else
- Trygon Prime can taken as HQ/HS
- Trygon tunnels can be used by all infantry/beasts but Raveners can be held until a tunnel is available.