demiurge1138
Inventor of Super-Toast
I'm not sure we actually have to make it act like a swarm. It could just do automatic damage plus poison to anything it grapples, and make the hundreds of surging spiders more flavor-text than anything else.
Adhesive (Ex): An arucha exudes a sticky slime that holds fast any creature or item touching it. It automatically grapples any creature it hits with its slam attack. Opponents so grappled cannot get free while the ooze is alive. The ooze makes one additional slam attack each round against any creature stuck to it.
A weapon that strikes an arucha sticks fast unless the wielder makes a DC 20 Reflex save. A successful DC 20 Strength check is needed to pry it off. The save and check DCs are both Constitution-based and include a +4 racial bonus.
The adhesive can be weakened by alcohol, but even in such a case the ooze gets a +4 bonus on grapple checks (for a total bonus of +9). The substance breaks down 5 rounds after the ooze dies.