"M" is for "Molewrath"

Molewrath

No. Enc.:  1d4 (4d10)
Alignment:  Neutral
Movement:  105' (35')
  —Burrow:  45' (15')
Armor Class:  7
Hit Dice:  15
Attacks:  3 (2 claws, 1 bite)
Damage:  1d12 / 1d12 / 4d6
Save:  L8
Morale:  10
Hoard Class: 
XP:  6,900

The surly, desert-dwelling, 20' long molewraths spend their days excavating massive den complexes centered around clusters of nutrient- and moisture-rich mutant tubers.  They sometimes burrow up into outposts, dragging sentient plants to their dooms.

Being immune to temperature extremes, toxins, diseases, and radiation, molewraths make hardy steeds.  Many humanoid races (Crules, Waste Witches, Gheelids) ride them imperiously into battle.

Rumors persist about sentient "molewrath queens" that direct their nests telepathically.

Mutations:  Gigantism, Reflective Epidermis (Cold, Fire/Heat, Radiation)