I vote the safer way. If we came in fast and they fumbled their jump, that could lead to some serious falling action, or us having to make another pass which could take a very long time...
Besides, only three people have Abundant Leaping- Heph, Berserker, and Azrael. That leaves Melkor, Klez, Sirin, and Helios in the lurch, especially since any of those three could drop (and Azrael's not fully available anyways).
Ok, you guys join the action at the start of turn 5. Here is how it looks:
Melkor is blasting aweay at one door surrounded by spiders (that you will soon discover contains a harrassed Berserker, Hph, Azrael and Helios) whilst Sirin and Klez are trying to stop spiders swarming onto the walls- and hence your landing area- from another doorway. Despite all this, spiders are generally arriiving on the walls from other locations.
Burn- no, you're going to be very busy. Everyone has to go as is.
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Stairway Door
Klez (4/9/0) KW HL BB CC EE LR BT
Goncz GA-9 (4/9)
Sirin (6/5/33) CF DM ST LA HL HT DiM VG BB CC EE
Sloping Corridor
Heph (7/45) PW CF ST SE AL WW SC NO HL DiM VG HT 2
Berserker (9/46) ST SS BS IB HT 1 CF SE WW NO DiM LA
Knives
Sloping Corridor Door
Melkor (5/6/0) DM ST SS HT DiM HL CC LR BT EE
H&K (3/0)
Spiders in sloping corridor (by Heph): 4 (ten in reserve)
Spiders by sloping corridor (by door): 4 (nine in reserve)
Spiders by stairway door: 3 (five in reserve)
Spiders atop relevant part of walls: 4
Situation at turn 5. You will be able to land at turn 7. Heph and Berserker have emerged into the open!
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Stairway Door
Klez (4/9/0) KW HL BB CC EE LR BT
Goncz GA-9 (2/9)
Sirin (6/5/341) CF DM ST LA HL HT DiM VG BB CC EE
Sloping Corridor Door
Melkor (5/6/0) DM ST SS HT DiM HL CC LR BT EE
H&K (2/0)
Heph (7/45) PW CF ST SE AL WW SC NO HL DiM VG HT
Berserker (9/62) ST SS BS IB HT 1 CF SE WW NO DiM LA
Knives
Spiders by sloping corridor (by door): 7 (eighteen in reserve)
Spiders by stairway door: 4 (seven in reserve)
Spiders atop relevant part of walls: 8