When you are falling you take 1d8 HP damage per sq (= 1.5 m = 5 ft) fallen. You may attempt to soften the fall by making a Body DEX - Check of 10 + sq. If the fall is higher than 6 sq (= 9 m = 30 ft), you become dying. Your HP become 0, or less if the fall damage would reduce it to less.

Every 6 sq of falling you can use an AP.

When you fall into somebody, you each take half damage.

Example: Ranger Agaron falls 12 sq down. He gets 2 AP and uses 1 to heal himself to 20 of his maximum 32 HP. He doesn't have any actions that would help him reduce the fall damage, so he decides to not use the other AP. He rolls 12d8 = 55 for fall damage which would bring him to -35 HP which would kill him, because it is lower than his negative maximum HP of -32. All his hopes lie on the Body DEX - Check. He has +7 on Body DEX and needs to reach 10 + 12 = 24. He rolls 17 + 7 = 24 and succeeds. With the damaged halved to 27 he is now only dying with an HP of -7.