Sand Pit
Walking into the flat plains the ground begins to rumble and shake.
The sand gives way to a funnel and a Sand Hydra emerges from its ambush.
DC 14 Dex save to avoid tumbling to the bottom of the funnel and ending up prone. On a pass you do not fall and can keep your footing.
Every round a d10 is rolled. On a number greater than 6 a nest of nearby Bullettes are drawn by the noise and tremors created by the fighting. They appear at the start of the next round.
On a perception check greater than 19 (Stealth Check for Hydra) you notice a pair of eyes staring right at you. As you watch they slowly close in a blink and you momentarily lose complete track of them.