This is begging for a giant version

[Shade]

Freaky!

This ancient insect was a chimera

"It has the long spindly legs of a praying mantis, something that would be useful, since its discoverers believe that it hunted by sneak attack. It had the body and wing shape of a dragonfly, which might have helped it rise and strike from the hunters blinds that it dug into the mud along the edge of the river."

 

[Cleon]

Freaky!

This ancient insect was a chimera

"It has the long spindly legs of a praying mantis, something that would be useful, since its discoverers believe that it hunted by sneak attack. It had the body and wing shape of a dragonfly, which might have helped it rise and strike from the hunters blinds that it dug into the mud along the edge of the river."

Why not!

A Giant Praying Mantis with upgraded aerial combat ability would seem at least a fair match to the adult, and the larva could use the stats for a giant dragonfly nymph.

 

[Shade]

Giant Coxoplectoptera, Adult
Large Vermin
Hit Dice: 4d8+4 (22 hp)
Initiative: +2
Speed: 20 ft. (4 squares), fly 60 ft. (good)
Armor Class: 16 (–1 size, +2 Dex, +5 natural), touch 11, flat-footed 14
Base Attack/Grapple: +3/+10
Attack: Claws +5 melee (1d8+3)
Full Attack: Claws +5 melee (1d8+3) and bite +0 melee (1d6+1)
Space/Reach: 10 ft./5 ft.
Special Attacks: Aerial sprint, improved grab
Special Qualities: Darkvision 60 ft., vermin traits
Saves: Fort +6, Ref +3, Will +3
Abilities: Str 17, Dex 15, Con 13, Int —, Wis 14, Cha 11
Skills: Hide +2*, Spot +6
Feats: —
Environment: Temperate and warm marshes?
Organization: Solitary
Challenge Rating: 3
Treasure: —
Alignment: Always neutral
Advancement: 5–8 HD (Large); 9–12 HD (Huge)
Level Adjustment: —

Aerial Sprint (Ex): Once per hour, a giant coxoplectoptera can fly five times its normal speed (300 feet) when it makes a charge.

Improved Grab (Ex): To use this ability, a giant coxoplectoptera must hit with its claws attack. If it wins the ensuing grapple check, it establishes a hold and makes a bite attack as a primary attack (at its full +6 attack bonus).

Skills: A giant coxoplectoptera has a +4 racial bonus on Hide and Spot checks. *Because of its camouflage, the Hide bonus increases to +12 when a coxoplectoptera is surrounded by foliage.


Since it "had the body and wing shape of a dragonfly", I split the difference in the physical ability scores between the mantis and the giant dragonfly (Dragon mag version). I added in the +4 racial bonus on Move Silently checks from the giant dragonfly.

 

[Cleon]

Giant Coxoplectoptera, Adult

Since it "had the body and wing shape of a dragonfly", I split the difference in the physical ability scores between the mantis and the giant dragonfly (Dragon mag version). I added in the +4 racial bonus on Move Silently checks from the giant dragonfly.

Giving a dragonfly a racial bonus to Move Silently makes little sense to me - the normal sized buzz pretty loudly when they're flying!

Presumably they did it because the original AD&D monster had a raised chance to surprise, but I'd have preferred a different approach.

It would make more sense if it just keeps still until a victim comes within a single-move flying distance, and then dashes out to attack by surprise.

We could give it a "Sprint" type ability so it can fly further than its normal allowance, e.g.:

Sprint (Ex): once per hour, a giant coxoplectoptera can fly five times its normal speed (200 feet) when it makes a charge.

Actually, I'd like to increase the fly speed a bit since we're making it an aerial predator. Maybe raise it to fly 50 ft. or 60 ft., which would make the Sprint 250 or 300 ft.

In either case, I'd drop the racial bonus to Move Silently.

 

[Shade]

I like it! I'll update the stats above.

 

[Cleon]

I like it! I'll update the stats above.

That'll probably do it for the mechanical elements of the adult.

 

[freyar]

Pretty cool! Doing a larval version?

 

[Cleon]

Pretty cool! Doing a larval version?

Yes, although it'll be pretty much like the dragonfly nymph conversion we did.

 

[Shade]

Yes, although it'll be pretty much like the dragonfly nymph conversion we did.

I can't recall that one. Did we do a dragonfly conversion?

 

[Cleon]

I can't recall that one. Did we do a dragonfly conversion?

I guess I was getting it confused with the dragonfly larva conversions in Athas.org's Terror of the Dead Lands. That does have the benefit of being sort-of approved by Wizards.

The Athas version is a terrestrial creature, unlike a real Dragonfly Nymph, but it is a simple matter of adding a Swim speed and the Aquatic subtype

DRAGONFLY LARVA, GIANT
Small Vermin
Hit Dice: 4d8 (18 hp)
Initiative: +0
Speed: 20 ft. (4 squares), climb 10 ft.
Armor Class: 15 (+1 size, +4 natural), touch 11, flat-footed 15
Base Attack/Grapple: +3/+0
Attack: Bite +5 melee (1d6+1)
Full Attack: Bite +5 melee (1d6+1)
Space/Reach: 5 ft./ 5 ft.
Special Attacks: —
Special Qualities: Darkvision 60 ft., vermin traits
Saves: Fort +4, Ref +1, Will +1
Abilities: Str 12, Dex 10, Con 11, Int —, Wis 10, Cha 2
Skills: Climb +9, Hide +4*, Spot +5
Feats: —
Environment: Mountains and rocky badlands
Organization: Solitary
Challenge Rating: 2
Treasure: None
Alignment: Always neutral
Advancement: 5-7 HD (Small); 8-10 HD (Medium)
Level Adjustment: —

The toothless, immature larva of some large bug, this three-foot-long creature appears tranquil and harmless.

Giant dragonfly larvae seem like feeble, toothless bugs, but in truth, they are at least as vicious as their parents. They appear toothless because of a strange, tentacled, fleshy organ that covers most of their mouth. Giant dragonfly larvae are normally greenyellow in color, but can change the color of their carapace to better hunt.

Giant dragonfly larvae begin life by eating their way out of a corpse. They are rather small when they chew out of their host, no more than 6 inches long, but over the next two weeks they grow in leaps and bounds, ending up over 3 feet in length. At that point, they stop growing and being preparing to molt. They consume as much organic matter as they can, preferring flesh but eating whatever they can. They have been known to kill an erdlu or erdland and feed off of it for several days. After 2 months of eating, they find a secluded place and, using the fleshy organ above their mouth, create a cocoon the size of a barrel. In about 10 days a fully formed giant dragonfly emerges.

Combat
Giant dragonfly larvae are ferocious in combat, growing more vicious as they come closer to pupating (cocooning). They strike at creatures that appear wounded, old, or sick. They prefer ambushing prey, using their natural camouflage while lying in wait. Larvae rarely retreat, but they will if seriously outnumbered.

Skills: Giant dragonfly larvae have a +5 racial bonus on Spot checks and a +8 racial bonus on Climb checks. They can always choose to take 10 on Climb checks, even if rushed or threatened.

*Larvae receive a +4 racial bonus on Hide checks when camouflaged in their natural surroundings.

From Terrors of the Dead Lands (edition 3.5, version 1.0)