This week i have been working on fleshing out both the wilderness survival / resource management challenge and the storm / Hydra encounter wile aboard the Golden Wave in The Hunt for Cofre Del Mar portion of the campaign.
Before we go any further I have to admit that I have taken most of the following ideas from my DM, who goes by the handle
Luz on these forums, and our on going Blackmoor game (Crystal Shard/ PotA).
At the beginning of the journey the Golden Wave will be loaded with enough fresh water and food for ten days, and wile on the ship the players will be expected to pull their weigh. First the players will need to decide whether they work night shift or day shift. Next I will encourage each of them to use their imaginations to choose a job on board, if they are totally stumped I will step in with a few suggestions. Depending on their specialties a player may choose to be on watch duty up in the crows nest. If they have proficiency in navigators tools or sea vehicle, possibly working steering the ship. Cooks utensils, gally. No matter what your job is, everyone on duty for that shift (including the NPC's as a single group) will need to make a group check, with at least 50% sucsess, or become lost. Becoming lost means you spend more time sailing, more chances for random encounters and more resources consumed. Some one could even possibly use a charisma check to boost moral and give everyone on that shift advantage on their survival checks.
The point is to try and encourage the characters to look beyond their characters combat abilities. If the party does not get lost then they will encounter the Cofre Del Mar 7 days into their journey. If they are caught out on the sea with no rations, they will begin to gain one level of exhaustion a day. Which makes it harder for them to sucseed on their group checks, which in turn makes for a longer journey back home, leading to more exhaustion and so on.
In stead of doing both separately an idea i had was to combine the Hydra encounter with the luck /hero point mechanic I described in the storm encounter from my last post.
The encounter would occure during the night shift. A natural heavy fog would roll in (possibly not the first time this has occurred to make it less alarming). Wile trying to navigate out of the fog the Golden Wave would strike a submerged Aquatic Hydra. The monster would stay submerged and after a few turns to shake off the stun it would begin to pick people off the deck one by one, or at least giving them a good chomp. After a few rounds of this, the Hydra will rear its 8 ugly heads, at which point either the captain or the fist mate will have no intention of sticking around and order all hands on deck for full speed away. Before speeding away the Hydra will take a few chunks out of the hull of the ship.
This will begin a chase sequence, but not the type described before on the docks with the barge. To remain out of the reach of the Hydra the party will have to come up with innovative solutions to help the ship moving fast. Either take to the riging and help unfurl the sails, go below deck to patch up the hole the Hydra made and pump out the water, Or they can try to disrupt the hydras advance with attacks off the bow. The Hydra if it catches up will be trying to bite at both any one on deck and also the ships hull.
Eventually the sea monster dives below the surface and one round later pops up on the side of the ship, tipping the entire boat on a 45° angle. This would beginning the third phase and each PC would receive luck points equal to their level (probobly about 5) that may be used on their turn. A player must decide whether they will use some or none of their luck points before any die rolls or other actions are made.
Luck points may be used like so:
1 luck point - advantage on any one d20 roll
2 luck points - auto success on any one d20 roll
3 luck points - improvise an action or feat normally beyond the characters means; something heroic. DM's discretion
When spending luck points, it must be accompanied with a colorful explanation. Without a good explanation the roll will automatically fail.
Each player depending on their location will face a unique challenge. Wile the players are dealing with each of their mishaps the Hydra will be tied up fighting the crew but if anyone ends up in the water the Hydra will hone in on them. Because of the severity of the situation casting a spell requires a DC 10 + spell level concentration check. If it fails is treated as a magic fumble. Players can avoid this by using luck points.
Up the mast:
When the ship tips, the player is flung threw the air towards the sea. The only thing stoping him from being flung into the water is a section of Woden beam in the characters path. He may let the beam catch his fall (suffering a broken arm) or spend luck points to grab the beam without injury. On the following round at the beginning of his turn the beam snaps. The PC must Grasp at the splintered stump of the beam with his good hand, which digs sharp splinters into him for 1d4 points of damage per round. A DC 18 str saving throw is required to pull himself up and a DC 10 Con save to avoid letting go.
On deck:
Two PC's are thrown, smashing into one another and then onto the deck before getting tangled up in one another and tumbling towards the ocean. The first PC is upside down, being held by the second PC who's cloak has caught on the ships steering wheel but it's ripping rapidly. Both are dazed from the fall and may only move or take an action but not both and neither may take a bonus action. Dex saves and checks have disadvantage. At the end of the following round the cloak rips and both players fall into the ocean if they can not work together to come up with a solution.
Below deck:
Wile below deck fixing the hole, the rocking of the ship causes a stack of supplies to come loose and tumble down pinning the players leg, inflicting terrible trauma as he struggles. He may Sacrifice the foot or use luck points to free himself. At the beginning of the next turn more crates threaten to burry the PC unless he makes a DC 15 Str Athletics check to throw the crates off him and a DC 15 Dex save (with disadvantage if foot is broken) to avoid further falling debris. If he doesn't manage to avoid this he takes massive bludgeoning damage, and the Str check to get out becomes DC 25.
Pump room:
When the ship tilts it takes on a huge amount of water. It comes crashing down on the PC from above. The crushing weight of the water stuns the player and it is so sudden and unexpected that unless he uses luck points he can not get a full breath and begins drowning at the beginning of his turn. The room is full of water and unless the pump is operated with a successful DC 18 Athletics check water will continue to fill higher decks. Water fills at a rate of a 1/4 deck per round, and the pump clears 1/2 a deck per round (so the water level only goes down by a 1/4 deck). Until the Hydra is pushed off the deck the ship continues to take on water.
Once the party is out of its various predicaments they will need to kill or at least fend off the Hydra. Wile the sea monster remains on the deck and the ship tilted any walking around the ship is difficult terrain. Any running, as in a dash, requires a successful Acrobatics check or fall towards the lowest part of the ship. If your on the top deck this means into the water but it also means there are plenty of hanging ropes, ringing and masts to swing from.