Maybe a shambler is the same as a shambling mound, but the huge gap in HD makes me think that it's not the case. Even more puzzling, they are about the same size. Surely, the lesser one should be smaller. Actually, I don't see why this type of monster couldn't be of any size. In this case, a range of HD would be appropriate. HD 3 to 6 for the lesser shambling mount, HD 7 to 11 for the Shambling Mound and the Shambler remains the biggest of the lot?
chiisu81 wrote: ↑Thu Jul 30, 2015 3:27 pm Copying Solo's entry from here.
Shambling Mound, Lesser
Armor Class: 19
Hit Dice: 3**
No. of Attacks: 2
Damage: 2d4/2d4
Movement: 20'
No. Appearing: 1d4
Save As: Fighter: 3
Morale: 9
Treasure Type: C
XP: 205
Shambling mounds, also called shamblers, appear to be heaps of rotting vegetation. They are actually intelligent, carnivorous plants. A shambler’s brain and sensory organs are located in its upper body. A shambler’s body is about 6 feet tall when the creature stands erect. It weighs about 500 pounds.
Shamblers are immune to lightning, and in fact gain a hit die each time they are attacked by lightning, up to a maximum 3 additional hit dice; these hit dice are lost at a rate of one per hour, while hit points granted in this way are used first when the monster is attacked. Further, they are resistant to both cold and fire, suffering no damage on a successful saving throw, or half damage if the save fails.
If a Shambler hits with both its attacks against the same creature, that creature is engulfed by the monster. The victim can no longer attack or cast spells, and suffers 1d6 points of damage each round due to suffocation. A shambler can only engulf creatures of man-size or smaller, and may only engulf one such creature at a time; the shambler will expel any such creature from its body 1d4 rounds after the victim dies. Attacks against a shambler which has engulfed a victim require a saving throw vs. Death Ray for the victim each time the monster is hit; if the save fails, the victim suffers half (rounded down) of the damage done to the monster (which still takes full damage). The victim does benefit from the monster's resistance to fire or cold, but takes full damage from lightning attacks.
Feel free to work on that one, among others. Please remember to check over the 
