Tyranny of Dragons

Both wights' arrows find their mark and Guard Drake 1 dies. 

Akkron directs them to repeat the procedure for the second drake.

Necrotic Bow vs. Guard Drake 2
Attack: 21 Damage: 10 (piercing) + 2 (necrotic) = 12
Attack: 18 Damage: 13 (piercing) + 6 (necrotic) = 19

Necrotic Bow vs. Guard Drake 2
Attack: 24 Damage: 21 (piercing) + 9 (necrotic) = 30
Attack: 24 Damage: 10 (piercing) + 11 (necrotic) = 21

Quote from Mister_Whisker >>

Akkron directs them to repeat the procedure for the second drake.

Necrotic Bow vs. Guard Drake 2
Attack: 21 Damage: 10 (piercing) + 2 (necrotic) = 12
Attack: 18 Damage: 13 (piercing) + 6 (necrotic) = 19

Necrotic Bow vs. Guard Drake 2
Attack: 24 Damage: 21 (piercing) + 9 (necrotic) = 30
Attack: 24 Damage: 10 (piercing) + 11 (necrotic) = 21

Guard Drake 2 dead

Akkron orders the wights to complete "Operation wipe out the stupid lizards," targeting Drake 3

Necrotic Bow vs. Guard Drake 3
Attack: 14 Damage: 10 (piercing) + 2 (necrotic) = 12
Attack: 14 Damage: 12 (piercing) + 3 (necrotic) = 15

Necrotic Bow vs. Guard Drake 3
Attack: 11 Damage: 15 (piercing) + 8 (necrotic) = 23
Attack: 9 Damage: 15 (piercing) + 4 (necrotic) = 19

Quote from Mister_Whisker >>

Akkron orders the wights to complete "Operation wipe out the stupid lizards," targeting Drake 3

Necrotic Bow vs. Guard Drake 3
Attack: 14 Damage: 10 (piercing) + 2 (necrotic) = 12
Attack: 14 Damage: 12 (piercing) + 3 (necrotic) = 15

Necrotic Bow vs. Guard Drake 3
Attack: 11 Damage: 15 (piercing) + 8 (necrotic) = 23
Attack: 9 Damage: 15 (piercing) + 4 (necrotic) = 19

 Since the lizard almost certainly isn't dead, he whispers orders for a second volley

Necrotic Bow vs. Guard Drake 3
Attack: 24 Damage: 15 (piercing) + 14 (necrotic) = 29
Attack: 19 Damage: 14 (piercing) + 1 (necrotic) = 15

Necrotic Bow vs. Guard Drake 3
Attack: 19 Damage: 10 (piercing) + 2 (necrotic) = 12
Attack: 22 Damage: 14 (piercing) + 1 (necrotic) = 15

All guard drakes dead and all 3 festooned with dark arrows.

Akkron nods... a job well done.

Come, let us clear the tower. Then we will rescue the prisoners. We will walk like a regular patrol through the area. Then I will enter the tower and take care of whoever is inside.

Akkron and the two wights, still under the effects of Seeming begin moseying nonchalantly around the perimeter, doing their best to stay hidden without looking like they're trying to hide. When they reach the tower, Akkron will approach.

Is there a staircase, or just a ladder?

The two wights will attempt to climb the hill and secure a rope for Akkron.

Wight 1 Athletics: 16
Wight 2 Athletics: 18

Both Wights make it to the top and lower a secured rope for Akkron. Perhaps not very gracefully done but Akkron makes it to the top. A short distance away you see a long wooden ladder that leads up onto the walkway around the watchtower proper. Faint dim light spills out from the watchtower. You do not see anyone from below.

Akkron is still disguised, so he simply climbs up the ladder, like a soldier coming to relieve whoever is on duty or give them a break. A dragon soldier climbing up the ladder shouldn't raise immediate alarm bells.

You see 4 masked cloaked people. They turn to you with one asking, "Why are you here?" 

Akkron casts Charm Person at 4th-level on the four of them.

They are all charmed 

Akkron would smile if his cheek bones weren't skeletonized.

The prisoners are being moved, he tells the four guards on watch curtly. I wanted to give you four a heads-up to avoid needless confusion. There is nothing you need to do here.

Please roll Persuasion with Advantage. 

Persuasion: 14 

Akkron will go ahead and use a Knowledge from a Past Life to boost that by 4

"I did not hear anything about that from Lord Mondath, but I suppose we were not told yet. I assume she has told the others as well. Message received, you can go about your business." says the cultist. 

The 4 go back to work peering outside for any signs of trouble. 

Akkron returns to the clearing, sliding down the rope inelegantly.

As soon as he is there, he steps up to the prisoners as if he belongs there. The drakes have been neutralized and the tower's guards charmed.

Cut them loose, he tells the two wights. We're moving them out of here. Quickly. We have no time to lose.