I had the same thought re: hazards, but you know how Shade hates those.
Damaging entanglement? Might work, sure.
1HD and Small to start is fine by me, too.
Okay then, how's this for a first draft:
I've set the advancement so they start out with 1HD per square of Space (e.g. a Large 10' by 10' plant will have 4+ HD). I'm thinking patches of these things could get enormous, so I'm having them Advance to Colossal.
Left the Attack line empty on the basis they only attack with their SA, but we could add a Tendril and Constrict attack if we wanted to.
Strangle Vine
Small Plant
Hit Dice: 1d8+4 (8 hp)
Initiative: +0
Speed: 0 ft. (immobile)
Armor Class: 11 (+1 size), touch 11, flat-footed 11
Base Attack/Grapple: +0/-4
Attack: —
Full Attack: —
Space/Reach: 5 ft./5 ft.
Special Attacks: Strangling vines
Special Qualities: Blind, plant traits, tremorsense 20 ft.
Saves: Fort +3, Ref +1, Will +0
Abilities: Str 10, Dex 12, Con 13, Int --, Wis 8, Cha 3
Skills: —
Feats: Toughness (B)
Environment: Warm or temperate woods and swamps
Organization: Solitary
Challenge Rating: 1/2
Treasure: 1/10th coins; 50% goods; 50% items [
incidental remains of prey]
Alignment: Always neutral
Advancement: 2-3 HD (Medium); 4-8 HD (Large); 9-15 HD (Huge); 16-24 HD (Gargantuan); 25-36 HD (Colossal)
Level Adjustment: —
Here's a go at the Strangling Vines SA. I haven't decided whether severing the vines should do half-damage to the monster (à la a kraken's tentacles) or whether it just takes whatever damage is done to the vines.
Which do you prefer?
Strangling Vines (Ex): Any creature that enters the reach of a strangle vine must succeed at a DC10 Reflex save or be seized by its vines. If they succeed, they must check again every round they remain within the plant's reach. Seized creatures are entangled and immobilized by the vines, and take 1d4 bludgeoning damage per round from being "strangled". A seized creature can escape by succeeding at a DC14 Strength check or a DC14 Escape Artist check. They can also break free by killing the strangle vine or cutting the vines that hold them; the vines are AC13 and have 4 hit points (8 hp for Medium strangle vines, 12 hp for Large, 18 hp for Huge, 24 hp for Gargantuan and 30 hp for Colossal).
[1] Severing the vines does half the vines' hit points in damage to the main plant. [2] The strangle vine takes any damage that is inflicted upon its vines. The save DCs are Strength-based and include a +4 racial bonus on the Strength and Escape Artist checks.