Viragon
The Viragon is an enormous Tyranid worm-like organism capable of tunneling through the ground akin to the more well-known Trygon. You would think that the Nids have enough tunneling units already and should be in dire need of more artillery units that does not suck donkey dick or more heavy psychic units that is actually worth something, unlike a certain other unit.
Appears only in the CCG, but it looks right gribbly and ripe for conversion.
Tabletop Fan-Rules
Some fan-made rules can be seen here. Although quite outdated.
Viragon
Pts/model: 280 points WS: 4 BS: 3 S: 8 T: 7 W: 5 I: 3 A: 2 (3) Ld: 10 Sv: +4 Heavy Support: A Viragon is a Heavy Support choice for a Tyranid army. Brood: 1 Viragon. Weapon-symbiotes and biomorphs: 1 set of Scything Talons (+1 attack), Toxic Miasma and Phage-cell Regurgitation. SPECIAL RULES Phage-cell Regurgitation: Viragons are specially evolved to carry a volatile cocktail of acids, phage cells and tyranid-based viruses. It sprays these out its maw coating everything in a contagious slime. Phage-cell Regurgitation uses the following profile: Rng: Template (Normal games), Hellstorm Template (Apocalypse) Str: 7 AP: 3 Type: Assault 1
Swallow Whole: Viragons have a split-jaw and are capable of swallowing men whole to digest and provide a source of nucleofourtides for the production of Phage Cells. If the Viragon hits with two of its attacks in the Assault phase, it can choose a single enemy model in base-to-base contact and swallow it whole! (no need to declare beforehand; this is an option you can elect to use if you roll enough hits). The Viragon scores no other hits if it swallows an enemy, as it is entirely engaged in cramming the unfortunate victim into its maw. The swallowed model is removed as a casualty, with no roll to wound made. Armour and Invulnerable Saving throws do not apply and wargear such as bionics cannot save the victim.
Gargantuan Creature: As a Gargantuan Creature, all the rules for gargantuan creatures apply to the Viragon. Fearless: Almost nothing can stop a rampaging Viragon; they are Fearless. See page 75 of the Warhammer 40,000 rulebook. Slow and Purposeful: The Viragon's huge bulk and muscular tail let it drag itself across the battlefield. See page 76 of the Warhammer 40,000 rulebook. Feel No Pain: The Viragon's armour and flesh is covered in a gelatinous slime that spreads the force of incoming projectiles across the surface of its body lessening the blow. See page 75 of the Warhammer 40,000 rulebook. Deep Strike