Craft Wands of Magic Missiles
If you're willing to sacrifice your soldiers, time and money, you might like to consider hiring or kidnapping craftspeople to Craft Magic Items. Specifically, Wands of Magic Missiles because it is an uncommon item which means that it is relatively cheap and easy to make, yet it has high reliable damage few creatures can resist. The cost of creating WOMM is much less than acquiring rare and obscure poisons and it is hundreds of times more effective than acid vials.
A Wand of Magic Missile has:
7 Charges. While holding it, you can use an action to expend 1 or more of its Charges to cast the Magic Missile spell from it. For 1 charge, you cast the 1st-level version of the spell. You can increase the spell slot level by one for each additional charge you expend.
This means that each wand when fully discharged as a Level 7 spell does 9d4+9 force damage at a range of 120 ft. That averages out to 27 force damage per wand.
A Kraken with unrolled HP has 472 hit points, thus if you can craft 18 Wands of Magic Missiles, and each wand is discharged as a level 7 spell, you should be able to kill the Kraken from 120ft away in a single round 50% of the time.
If you fail, use your range to try and escape with all your wands and attempt again the next day. A Kraken can dash swim 120ft in a single turn so leave some goblinoids as bait to slow it down (and also to absorb hits from lightning storms) or strike from the shore.
Crafting WOMMs will require:
XgtE Version pg 128, 129
- A formula to create wands of magic missiles
- A craftsperson proficient in the Arcana skill
- Facing a CR 4-8 encounter each time to gather components for each wand. You have 1800 goblinoids so this should not be a problem. You only need 18 wand users so even if you lose half your army this way it won't matter when you face the Kraken.
- 200gp for each wand. 3600gp for 18 wands
- 2 Workweeks per wand per craftsperson. 36 weeks for 18 wands worked on by one slave... I mean craftsperson
DMG Version pg 128, 129
You can also find another set of rules on crafting magic items in the DMG (pg 128, 129)
To craft Wands of Magic Missiles that way you'll need:
- A formula to create Wands of Magic Missiles
- A spellcaster level 3 or higher that can cast Magic Missiles
- 500 gp per wand. 9000 gp for 18 wands
- 20 days per wand. 360 days for 18 wands with one craftsperson
The creator of the wand must spend one spell slot of the spell's level on the item being created each day of the creation process.
As you can see, the DMG version is more expensive and requires more time but you do not have to risk your army.
The more wands the better!
If you craft 53 wands, you will be able to burst down a Kraken 100% of the time in a single round if every fully charged wand is completely discharged as a level 7 magic missile spell at a non-rolled HP Kraken that round.
In fact, an army with enough magic missile wands can burst down just about anything you come across in 5th edition!
While discharging the WOMM at lower levels over several rounds will result in overall higher damage, keep in mind that this comes at great opportunity costs when fighting legendary creatures. A Kraken will be able to close into your ship in a single dash even if you had casted Magic Missiles from maximum range. Its legendary actions every round and Siege Monster trait means that it can very quickly destroy your ship! So burst it down in as little time as possible.