Lets kill the party!

party wakes up on a deserted island no items

dc 15 investigation will find a hidden trap door
dc 20 they notice trap
they can attempt to disactivate it with a dc 10 slight of hand
if the trap is triggered then anyone in a 5 ft must make a
dc 15 dex saving throw or take 3d4 damage from falling coconuts and become poisoned

a cure for the poison can be found on by
searching on the island with a dc 15 nature check

the trap door has a rope ladder that leads into a massive cavern
with large flowing water falls.

The party can also find the cavern by trying to build a boat or swimming off
the island. After getting about 100ft from the shore will  be sucked into a current and fall into the cavern taking
2d6 fall/drowning damage

The cavern is illuminated by soft purple glow from the petals of
exotic plant. On closer inspection the party can see
large thorn coming of the plants with a dc 15 nature check the party can learn
that this is the same plant that the poison from the earlier is made from
this plant, on a dc 20 they know how to make the poision but it will also require a
dc 20 slight of hand to avoid the thorns. If they fail the slight of hand
they take 1d4 damage and become poisioned. They still get the crucial ingrediant to
make the poision but they still have to deal with being poisioned themselves

In the center of the cavern is a stairwell leading into the heart
of the earth. Etched into the the rim of the stairs "BEWARE THE BLIGHTED
LIZARD"

20 steps down the stairs is a pressure plate that will send a barrage
of darts at the party

Shortly after is a door once inside the door will slam shut behind the party.
In the middle of the room is a small pressure plate that has a picture
of a bucket with the number 4 etched into it
behind this is a well and two buckets one 5(A) gallon and one 3(B) gallon.

Sollution: the party must fill up the 5 gallon bucket it with 4 gallons
of water and place it on the pressure plate.
fill B(A0B3). B->A (A3B0). fill B(A3B3). B->A(A5B1). empty A(A0B1).
B->A(A1B0). fill B(A4B0).
Apon doing so the party will open the main door and reveal a hidden
hole in the wall. There they will find some gold and a number of antidotes
equal to the number of party members.

Further down the staiwell the party will find another door. Inside this
door the party will see a gleaming sword hanging in mid air. If the party walks
into the room without investigation they will find themselves inside a genatinous
cube. The sword is magical or somthing strong that will help the party
fight the final bosss.

Further down the stairs the party will start to hear loud buzzing sounds.
Inside the next door the party will find themselvs greeted by a stange man
who calls himself the crypt-keeper. He will congradulate the party for making this
far And comment on how it has been ages since adventurers have made it to him. And
recounts the tale of how his own party came here years ago and they each died off
to different challenges that the party has overcome already. If the party tries to fight the
crypt keeper he will blow a horn that will summon many swarms of wasps
to come out of holes in the stone to assist him in the fight. The party can also
try to persuade the old man and he will come assit in the comming challanges.
He is a circle of the land druid.

Next the party has to fight something make it strong its the miniboss
They are rewared with somthing cool, lets magic a magic scroll and some gems

In the next room they party will find a group of dragon worshiping cultists. Half
of the cultist are surronding a mystical artifact of great power whispering strang chants.
The other half are draing a group of innocent peoples blood. If the party chooses to
help the innocent they will lose the artifact. If they choose to go after the artifact
they will lose the people. They can split and go after both groups. If they do
well enough in the fight they can save both. If they split and do poorly they
will lose both. If they save the artifact they get it. Its cool and powerful
and reduces the power of the final boss somehow. If they save the people they will
follow the party with them into with them to the final fight. If any of the party
dies during the fight they will risk their lives to stablize that party member with a potion
One potion per party member.

The next room has a large lake of poision. In the middle is a small island with
a glowing pedastool. There is a boat on the shore. The party can take the boat to
the middle island. They will be attacked by skeletons who will try to pull the party
members into the lake. In the pedastool is antidote as well as an encanted bow
of dragon slaying.

At the bottom of the stairs is a large chamber witha Adult Black Dragon guarding treasuree
and a portal that will take the party back to where they came from. The party can
choose to skip all previous rooms and fight the dragon from the get go
but it will be harder.
If an adult black dragon is too weak add two Adult green dragons.
If it is too strong then make the crypt keeper stronger? or tell them to man up
idk rocks fall dragon dies? some sort of balance maybe or not up to you