Spoiler time! Remember the novel Jurassic Park? If you do, you’ll remember park owner Hammond was not the genial grandfather of the movies—he was pretty much a bastard, and he came to a grim end at the hands (or rather teeth) of some procompsognathuses. (If that sounds familiar, it’s because they lifted that scene almost directly to torment a girl in the movie sequel.) What made the death possible was the compys’ soporific venom—one bite did little harm, but a succession of bites from a whole swarm of the tiny dinosaurs quickly overwhelmed Hammond.
Shocker lizards operate under the same principle. Alone they are little threat…but in a group they can generate more power and (quite inconveniently) become more territorial. This means they are both more likely to attack PCs rather than run from them and more likely to succeed in killing them when they do.
This ramp-up effect makes shocker lizards really lethal for a CR 2 monster—PCs who run into a colony can easily get the full 12d8 brunt more than once if they’re not careful. Of course, it’s probably nice for you to give them some warning this is possible. Have them encounter one shy shocker lizard…then two who give off warning shocks…then two who succeed in delivering a 4d8 lethal shock. Smart PCs will adjust their tactics and/or leave the lizards alone. As for dumb PCs…well, it’s not like you didn’t warn them…
A colony of shocker lizards has settled in one of the few reliable oases in the Behir Desert. When adventurers arrive, the territorial lizards scare off their camels, leaving the party low on supplies and with few options. Assuming they can defeat the shocker lizards, the adventurers find what drew the creatures to this oasis in the first place—a lightning-warded trove of suli scrolls and potions.
A wizard bred shocker lizards to appease his lonely familiar, but the reptiles quickly became too aggressive to tend. He has ceded the bottom two floors of his tower to them, and they have claimed the sewers beneath his home as well. He does not drive them off because they form a useful alarm system—in his mind, anyone worth speaking to already knows to levitate to his solarium on the third floor. Meanwhile, the shocker lizards are decimating the giant beetles that clean the sewer, with effects that are beginning to ripple throughout the subterranean ecosystem…
Spell-bowerbirds (treat as Young shocker lizards with a raven’s fly speed instead of climb) are large magpie-like birds that have a particular eye for objects with lingering traces of magic—from spell-scorched leaves and twigs to unattended magic baubles. These they collect and weave into the communal bower nests they share. Over time, the residual energies grant the birds a unique power: a magical burst of force (substitute for electricity in the stat block) as long as they are in contact with their nest. Thus while the birds are nearly harmless in flight, any adventurer who raids one of their bowers in search of a lost magic ring or trinket may soon regret that decision.
—Pathfinder Bestiary 248