Getting back to dark sprout here.

Attack: Tentacle +25 melee (2d6 + 18)
Full Attack: 4 Tentacles +25 melee (2d6 + 18)

Special Attacks: Breath Weapon (14d6 negative energy), Entangle, Swallow Whole

DC for saves for Entangle are 33 (The saves are dexterity based and include a +2 racial modifier). The racial modifier is the feat ability focus (entangle). 10 +14 + 7 +2.

I suspect that due to the very high DC of all the saves, the CR is above 20 and would be inclined to make it CR 24. Str and Con 34 are excessive for a CR 20 monster. Str or Con 34 is fine but this is more powerful than a black dragon wyrm (also CR 20) so I'd be hard pressed to keep it CR 20.

Breath weapons use Constitution modifier for their saves. DC is 10 + 14 + 12 = 36. It is 14d6 damage in chart but 1d6 in text. Taking 14d6 points of negative energy damage makes sense. How often can it use its breath weapon? With something this powerful it should be limited to three times a day, otherwise it's a Total Party Kill (TPK).

Advancement cannot be smaller than Huge. This is probably a better advancement: 29-40 HD (Huge), 41-56 HD (Gargantuan)

Ghost touch is an enhancement not an enchantment.

Death Throes seem awkward. If there is no save, you need to mention it.

Death Throes (Ex): Upon death, a dark sprout releases a burst of negative energy in a 60-foot radius that kills all normal vegetation and causes all nearby living creatures to take 6d6 points of negative energy damage. Furthermore, all Undead within range are healed for for 3d6 hit points. There are no saves.

Swallow Whole is also a bit off. What is the basis for the Reflex save? 24 is too low. I recommend Dexterity-based for DC 31 (10 +14 + 7)

Swallow Whole (Ex): If the dark sprout begins its turn with a grappled opponent in its tentacle, it can attempt a new grapple check. If it succeeds, it swallows its prey. A swallowed creature takes 2d4 points of negative damage each round and must succeed a DC 31 Reflex save each round or become stunned for its turn. A creature can attempt to cut its way out of the pumpkin, dealing piercing or slashing damage against an Armor Class of 22. If the creature inside manages to deal 50 points of damage, it can escape through the side of the dark sprout. A creature that cuts itself out of the dark sprout is still considered grappled. A swallowed creature is counted as grappling, whoever the dark sprout not. Due to its hollow form, a Dark sprout can swallow creatures of up to its own size. (1 Huge creature, 2 Large creatures, 4 medium creatures, 8 small creatures, and so forth.). The save is Dexterity-based.

That's all for now. More later.

Debby