Objectives
1. Save the Duke.
2. Save the friendly Mindflayer.
3. Save all the innocents.
4. Collect the vault key.

If I counted correctly there are 14 people to save.
You have the four directions and a party of four, so splitting the party is the way to go.

Location A: This is the most important location. This has the Duke and a random innocent.

Location B: This has the most innocents to rescue.

Location C: This has 2 innocents and a path to rescue the friendly Mindflayer.

Location D: Simply the path to E that has some fish monsters to fight.

Location E: More treasure and the vault key.

A Run Objectives:
1. Release Prisoner 1
2. Kill Champion 1.
3. Kill Hunter 1.
4. Release Prisoner 2.
5. Release Duke.
6. Heal Duke.
7. Save Duke.
8. Duke Escape.
9.Assist in keeping the Fish dead and Prisoners safe.

Turns Actions
1. Fly or take stairs down.
2. Jump to door.
3. Pull Lever
4. Use Misty Step or Fire an Arrow of Teleportation. You want to be next to the big champion fish guy. You may even be able to get a hit in depending on the character.

Turn 2.
1. Kill a hunter and go next to the lever on the side cell, not the middle one containing the duke.
2. Release the Prisoner 2.
3. Open the Duke's cage.
4. Heal the Duke.

Note: Moving the Duke out of the cell triggers the Warlock Pact Demon to show up and force the Duke to Kneel for some exploding spiders. Ensure he is healed before you move him out.



Turn 3.
P is prisoner. Hopefully they cleared the area.
D is duke. When you move him you want him to Jump (he has 20 str) far into the room. This will set off the cut scene.
X is where you should be. Heal the duke and move into the center of the room.

The red dots are where the spiders will appear. You want to be between them and the Duke.

You will have to Help the Duke get up from the kneel command. If you can heal him even more, then it should be very easy to get him out of there.

Turn 4+
You can Dimension Door the Duke once you helped him from his Kneel . Use can then use a scroll and make it even easier to get them back on board.

The Duke has 20 str and jumps very far. His movement with a Dash action will get him back on turn 5.

Your character should then make sure no fish monsters got past and are impeding fleeing prisoners.

Objectives.
1. Kill fish hunter1.
2. Free Prisoner.
3. Kill fish hunter 2.
4. Kill fish hunter 3.
5. Free prisoners.

Turn 1.
1. climb/fly down stairs.
2. Jump next to lever/ fish hunter 1.
3. Kill fish hunter 1.
4. pull Lever.
5. Movement to end of hallway to bring the other fish hunters into initiative.

Turn 2.
1. Kill fish hunter 2.
2. Move near lever but don't use it.

Turn 3.
1. Kill fish hunter 3.
2. pull lever
3. move and pull other lever.

Turn 4+
Escort prisoners back

Objectives.
1. Release both prisoners on Turn 2.
2. Kill the first two waves of fish guys.
3. Loot treasure.
4. Pick up tadpole specimen.
5. Rescue friendly Mindflayer.
6. Use friendly Mindflayer to teleport directly to submarine.





Turn 1. Make it to the X.

Turn 2. Release both Prisoners



Turn 3. Kill the X's in the room.(all 3 if you can manage).

Turn 4. Kill next wave of respawns and pull the lever.



Turn 5. Collect treasures and free the Mindflayer. Use Mindflayer to get back.

I used a warlock for this. Cone of Cold is particularly good for one-shoting the fish monsters. Fireball not as good in water.

Big powerful flashy spells is nice here.

These sections are completely optional.



Objectives.
1. Stall the fish monsters in room D.
2. Loot Room 1.
3. Loot Room 2.
4. Escape through route B.

Turn 1.
1. Trigger the combat in room D.
2. I like to summon something to distract them.

Turn 2.
1. Ignore the fishies and proceed to Loot room 1.

Turn 3.
1. Loot Room 2.

Turn 4+
1. Pull lever to open route B.
2. Escape.

Summoning something, somethings, or landing a big sleep spell or simply stealthily getting through is objective for this.

You have to have your characters and the prisoners moving fast to get through this in time.

Ways to speed up your characters.
1. Dimension Door. One Character can make Two Characters move pretty far in action.
2. Misty Step. Scrolls and spells. Great Bonus action.
3. Teleportation Arrows. Honestly these things are under-rated.
4. Jump. Might as well Jump. Go ahead and Jump. Jump potions help bad jumpers.
5. Fly. Flying is good. No terrain penalties from water and stairs.
6. Dash. When all else fails. Dash.

Ways to speed up prisoners.
1. Haste spell
2. Haste Potion.(you can throw it at them.)

Dimension Door does not work on prisoners. It does not work on restricted allies. If you want to sent 2 characters in a direction, they could both dimension door each other to double movement (they should be in same initiative order.

I brought my paladin, I know its the most popular class, to rescue the Duke at A. Healing is necessary and having options is good.

I had LaeZel as an Eldritch Knight go to B. Githyanki flight boots are fantastic. Ability to easily finish off the hunters quickly, high AC and ability to deal with getting netted easily. Throw healing potions. Use Scrolls and potions for movement boosts.

I had Wyll go rescue the mindflayer at C. His cone of cold one hit the fish that respawned.

I had Shadowheart be my looter at D/E. I summoned a planar Ally to distract Room D. She also was my lockpicker due to guidance and +3 dex modifer I templated her with.

You can close doors to prevent fishies from influencing your prison break. Shoot a fire arrow, cast a fire bolt, throw an Alchemist's fire at the Heat Detector's to close those doors.

You only want to close the areas 1 and 2.

Area 1 has continual respawns.
Area 2 is not a return path. A good way to close if your summon dies or looses aggro, or you went a sneaky route or ... something else happens where they could come to the center and start bothering retreating prisoners.

Closing Area 1 without the Mindflayer to teleport you directly back to the sub is riskier, but should be done as you can still retreat from lane B.

I played this level too many times.
My many reasons for restarting:
I had a good run and forgot to save after.
I had one prisoner get netted and killed.
I had my character's turn order before the NPC who had one last ladder to climb on the final turn. ( I dont know how to wait or lose place in initiative order).
I had some mis-clicks that ruined the first 2 turns that ment the prisoners were released on turn 3.
I had some characters get netted and Im not sure how/ or if it is worth it/ to solo get them out of the net. (turn 2).
I relied on Dimension Door and it failed or mis-click.
Used fire in the Heat Detector corridors.
Realized Fireball is weaker against wet mobs in water.
If you have a summon, and you enter the sub, the summon will appear there. This lets the monsters in D free to harass the prisoners.
If you use the Mindflayer to teleport you main character to the sub, you have to exit the sub and re-enter to begin the cut scene to leave.



Heres the final scene.

(spoiler picture)


Hope this helps.