From publisher blurb:
Wriggling, Writhing, Ravenous!
Mythic Worms brings you a variety of vermicious villains, from teeming tiny terrors like the clinging, blood-sucking leech swarm and the terrifying parasitic rot grub swarm with its invasive gestation. At the opposite extreme, the titanic giant purple worm embodies brutal strength and primal power, while the equally huge neothelid is a lurking alien menace of the deep places beneath the world, its wormy exterior belying an advanced alien intelligence. The sinister seugathi are spawned by the neothelids as their spies and slaves, but are formidable in their own right, and like them the vermlek demon is an infiltrator par excellence, wriggling inside the remains of its victims and wearing their mind and body as a fleshy suit until the moment they burst forth in a rain of terror and blood. The freezing frost worm is legendarily as deadly in death as in life, while the sizzling thoqqua bores through stone and steel as easily as flesh. Not truly worms, perhaps, the heaving bulk of the giant slug and the kaleidoscopic shell of the freakish flail snail are nonetheless a sight dreaded by adventurers of every stripe. Perhaps most deadly of all, the worm that walks embodies every part of wormish terror in the form of slain sorcerer risen again through the eldritch appetite of the worms that consumed his living flesh. To this collection of worms CR 3 to 21, we present the terrifying ghoul-spewing conqueror worm, a carrion crawler supreme that devours and regurtigates the dead as its feasting slaves. As if this were not enough, we also bring you rules for getting a wormish companion of your own, including a divine domain for your local cult of Worms and a set of feats for taming and riding wormish beasts!