Here's another piece I'd like your guys' feedback on. This is my take on a tyranid bastion and comms array. I thought about some kind of spore mine launcher, or a hive mound bristling with devourers and a venom cannon, but ultimately it felt more "tyranid" to me to go in a different direction:
TYRANID SWARM NEST
Whenever the tyranid swarm touches a planet for any length of time, microscopic tyranid spores begin to “tyrannoform” the surface. Flora of all kinds are warped and mutated in the image of the swarm. One of the strangest products of tyrannoformation is the so-called “brood nest.” Though they may appear to be a simple network of tunnels and caverns, a brood nest is actually a tyranid organism that gestates tyranid beasts directly on a planet’s surface. Cunningly concealed amidst the overgrown plants that accompany the swarm, a brood nest may be overlooked by an enemy until the very ground seems to erupt with tyranids fresh from their birthing sacs.
Some brood nests are small enough and penetrate the planet’s surface superficially enough that they may be killed by small arms fire (flamers tend to be particularly effective). Others are so extensive that, though living organisms, they may as well be subterranean cavern networks. These nests, sometimes nicknamed “swarm nests” by those unfortunates who have encountered them, can birth even the largest tyranid monstrosities, and are extremely difficult to kill—even sustained artillery fire usually does little more than kill the surface layers and bury them. Swarm nests are often accompanied by pulsing brain-like hive nodes, which seem to serve as a kind of psychic beacon that draws distant tyranids to the nest’s defense.
Swarm Nest Rules
Building: A swarm nest is a building with an Armour Value of 14 all around. As a building, it may be attacked just like a stationary vehicle. However, a swarm nest ignores all results on the vehicle damage table other than Destroyed, including Crew Shaken and Crew Stunned. A swarm nest may hold a single unit of any size of infantry, beasts, or monstrous creatures. A swarm nest may hold a gargantuan creature if the gargantuan creature’s unit will physically fit within the footprint of the swarm nest.
Access Points: The entire swarm nest functions as a single access point. This includes the surface of the swarm nest itself.
Fire Points: The entire swarm nest functions as a single fire point that can accommodate any number of models.
It’s Alive!: Models may stand upon a swarm nest (including models that have just disembarked from the nest itself). A swarm nest counts as clear terrain to tyranid units belonging to the player who placed the nest during setup. To all other units, the swarm nest counts as Dangerous Terrain, so riddled is the ground with exit canals, shifting musculature, and bizarre epidermal defenses.
A swarm nest may be occupied by any unit, subject to its normal transport capacity restrictions. However, models occupying a swarm nest other than tyranid models belonging to the player who placed the nest suffer a single wound (with normal saves allowed) on a d6 roll of 1 at the beginning of every turn. Units occupying a swarm nest may attack it in close combat whilst inside the nest. If they do so, the swarm nest’s Armor Value counts as 10, and rolls on the vehicle damage table receive a +2 bonus.
It’s … Huge: A single swarm nest can gestate a huge number and variety of tyranid creatures in a network of vile alien wombs that extends much farther than the above-ground portion of the nest suggests. Any tyranid unit belonging to the player who placed the nest during setup may treat the swarm nest as any table edge when entering play. Units that enter play through a swarm nest are assumed to have entered play within the nest itself. Note that while any number of units could enter play from a single swarm nest in a single turn in this manner, the swarm nest would have to be empty (or the unit entering play could not enter the nest) and each unit would have to vacate the nest to make room for the unit following.
If the swarm nest is occupied by a hostile unit when a unit attempts to enter the nest from off the board, the occupying unit is immediately assaulted by the unit attempting to enter the nest in this manner. In that turn’s Assault phase, the two units will fight a close combat, with all units (including any attached Independent Characters) counting as engaged with all other units, and neither unit counting as charging or moving through Difficult Terrain. The unit occupying the swarm nest also counts as engaged with the swarm nest itself. Units fighting within a swarm nest in this manner count as Fearless whilst fighting within the nest. Whilst a unit occupying a swarm nest is engaged with a unit attempting to enter play through that swarm nest, no other unit may attempt to enter play through that swarm nest (though it may attempt to enter play through another swarm nest, if more than one is on the table).
Units fighting within a swarm nest in this manner may not move until one or the other unit or the swarm nest itself is destroyed (note that the swarm nest itself may still be targeted by shooting attacks, and the occupying unit may attack the nest in close combat even whilst fighting the unit attempting to enter play through it). If the swarm nest is destroyed whilst a unit is attempting to enter play through that nest, the unit attempting to enter play is destroyed—still alive, perhaps, but buried beneath layers of rubble or dead tissue for the duration of the battle. The unit occupying the swarm nest when it is destroyed is treated normally.
Objective: In missions that use objectives, a swarm nest always counts as an objective.
Hive Node Rules
Creature: A hive node is treated as impassable terrain. However, it may be attacked like an infantry model. Units hit a hive node automatically in close combat, and do not become locked in combat after assaulting it. It has the following profile:
T5 W3 Sv5+
Psyker: A hive node is a psyker. It has the Synapse Creature psychic power.
Comms Array: So long as it is alive, a hive node allows the player who placed it to re-roll any and all Reserve rolls.
A few notes about my design decisions for this one. First, I decided to make the nest a building rather than an immobile creature with high Toughness and lots of Wounds because of the problem of sniper rifles. Even if I made the swarm nest T10 W10, heavy sniper fire could bring it down. I didn't like the idea of this vast, subterranean bulk being put out of action by thirty sniper bullets.
Second, as I said, I wanted to make the nest serve the "bastion" role without giving it any powerful guns, as that just didn't feel right to me. This is the main reason the nest ignores Crew Shaken and Crew Stunned - a tyranid player can, if he wants to, load it up with shooty bugs (or even a shooty carnifex) and produce a reasonably shooty building.
Third, I included the hive node comms array because I think a building like this would be much more flexible if you have greater control over your Reserves - particularly in Planetstrike, if your entire army is on the table on Turn 2, it doesn't much matter that new bugs can come in through the nest (unless you play using lots of Without Number gaunts, which not everybody does). However, I didn't like the idea of using a regular comms array, since it seems very un-tyranid-like to me to have some bugs sit back and man the radio (even if that radio is a pulsating alien brain). This way the hive node doesn't have to be manned, which feels more tyranid to me - but it's also an advantage, so I tried to compensate by allowing it to be destroyed, unlike a regular comms array. I'm not sure if I've struck the correct balance between making the hive node tough enough that a tyranid player can get some good use out of it, but fragile enough to balance out the advantage of an autonomous comms array.