Mucolid Spore
A Mucolid is a bigger kind of spore mine which is filled with evil bug gas that enables it to bumble around at much higher altitudes than their smaller relatives. This enables them to fling themselves after even the quickest of flyers and flying monstrous creatures with a propulsive blast of flatulence. Mucolid Spores despite their appearances can move swiftly through the air like a suicidal hot-air balloon, exploding with lethal force once they close with their target - making them a deadly obstruction for enemy flyers.
They work in conjunction with the Sporocyst. Essentially, when a Sporocyst has made planetfall, it will spread its chitinous shell and burrow into the ground like a tick in unprotected flesh. Once embedded, the Sporocyst coughs out clouds of polluting microorganisms that denature the planet’s atmosphere until the air is ripe for digestion. Of course the Sporocyst needs protection from potential airstrikes so the Mucolid Spore helps create a defensive shielding around the Sporocyst to potentially deter any enemy aircraft within its vicinity. This makes the only way to attack a Sporocyst viable is by land, and the Sporocyst is already heavily guarded by other forms of Tyranid bio-organisms as well as its plethora of bio-weapons.
They are allowed to assault flyers, automatically hitting them with a S8 AP3 large blast. They count as 3-Wound monstrous creatures, and they can be taken in broods of up to 3. Being troops choices, the Tyranid player can finally get all his Troops requirements out of the way for a breezy 30 points, leaving more room for more important things.