Move: Move to jump across the Pit, which I believe should be DC 10 with a running start (2+ squares of movement before jumping).
Athletics:
Rolled 1d20-1 : 17 - 1, total 16
If he passes:
Galadren lands on the far side and continues moving to C9.
Standard: Ready to fire a Biting Swarm at the first enemy he sees (Kneureg?)
To-Hit:
Rolled 1d20+6 : 20 + 6, total 26
Damage:
Rolled 1d8+4 : 7 + 4, total 11
Hit: Target takes -2 penalty to-hit.
If he fails:
Galadren falls into the darkness, twisting in mid-air to nimbly break his fall.
Acrobatics to reduce damage:
Rolled 1d20+9 : 8 + 9, total 17
Divide by 2 to determine how much damage is stopped.
Standard: Second Wind (Galadren regains 6 HP and gains +2 to all defenses)