To spice up an encounter (the "Confrontation with Demos" in ep. 2 of Dawn of Defiance), I am thinking of adding a couple of traps, namely two 2x2 trapdoors in the floor which Demos will immediately open if the heroes step on them. Some of the guards may also try to Bullrush the heroes over the edge if they get the chance. One of the players expressed disappointment that there weren't trapdoors in the floor of the throne room, not knowing he would have to fight there later, so I'm going to grant his wish :P.

My question is, what CL would you give a trap like this (i.e. how many XP are they worth)? The pits will be 6m (4 squares) deep, so 2d6 falling damage, and Climb DC 15 to get out. There is a CL table for traps on p5 of the Encounter Budget guide, but there doesn't seem to be an obvious slot for a trap that does 2d6 damage once only, has +20 to hit, and leaves you prone and stuck down a hole.

My party consists of six 5th-level heroes, none of whom are particularly good at climbing or acrobatics. Because DoD is designed for parties of four, I essentially need to increase the XP award for each encounter by 50% in order to keep them progressing at the right rate.

Thanks for your help.