The Broken Tower - Gameplay

Nathem , give me a scan and Listen roll

Whatever Passion, Rune or Skill you use to augment needs to be appropriate or at least something you can justify (as you might justify a Push roll in CoC). If doing something in defence of clan or family, for example, Nathem might call of his Love of Clan passion. With regards to sneaking, Nathem has a very high affinity with the Movement Rune, so might use that as inspiration. Note you can only call on an inspiration once in any given scene, but if it succeeds, the benefits apply to multiple rolls (a good example is in combat). The Bow is connected to the Fire rune (which Nathem has no affitinity with) but you might call on the Air rune to call on the elements to aid your aim.

Temporal spirit magic spells last for 2 minutes, so wouldn't have been much point casting earlier, so you can cast it now, before firing. Remember you can cast a spell and fire a bow in the same round, it just uses Strike Ranks. the spell is your Dex SR +1 per magic point after the first, which means Nathem can cast Speedart on SR1 then fire the bow on SR2, all pretty instantaneous, and as he has surprise, from his move Quietly roll, could do this before anyone reacts.
The use of a rune/passion etc is just something you state (and justify if need be) , make that roll first and based on that roll get a bonus or penalty to your next roll.

OK, as you can only see the head, we'll treat it as targeting a particular body part. that doesn't give a penalty, but you have to wait until SR 12 (meaning you can only get that one shot off.)

The enemy gets an opportunity to dodge but he is not quick enough.

That roll is a Special Success (with the Speedart bonus, your skill is 90 95 so anything under 1819 is a special. Special damage for an arrow is double rolls so another 1d8+1 please!

17 Damage! Nice! So after 4 armour on the head, that's 13 damage.

Correction, Speedart gives you another +3, 20 damage, 16 after armour. No man could survive a shot like that.

What is everyone else doing?

Not sure if you missed it, but Nathem told you he was going to cause a distraction on the east side allowing the rest of you to approach up the ramp, so unless Vasana is shouting to where he now is, he's not within speaking distance.