Zee nods slowly, wandering off down the flattened path to hide in the stalagmites. “Sure thing dude. I’ll try to drag it as far from shore as I can.” He kneels down, watching the water as he prepares to cast his spell.

Gulin moves over to Reynnar as the others prepare. "Lad, let me see your bow." He traces out a series of Dwarven runes in the air around the bow, which ignite in a glowing golden lines before settling on the bow itself. One rune, that for the "nj" sound in Dwarvish, forms a aiming crosshair, floating just off the side of the bow shaft.

Cast: magic weapon

Gulin nods at the elf and moves to stand next to Caspia, retrieving one of his pots of oil from his bag. He nods at the others. 

Reynnar nods to Gulin, pulls up his hood, then signals to Zee to light a torch he's placed on the ground. He then readies his fire arrows and prepares to light the first arrow and fire.

Moonday Goodmonth 16th, 591 CY

Gulin tosses a few of his rations into the water. The sound of the splash slowly reverberates throughout the cavern. Very small ripples dance across the surface of the water a few moments later. Everyone waits. Nothing happens.

Gulin retrieves his soggy rations from the water and throws them back. Once again the sound slowly reverberates throughout the cavern and slightly larger ripples appear across the surface. The increased size of the ripples gives the party false hope that their quarry is at hand, yet once again nothing happens.

Roughly five minutes have passed since the start of this ordeal. The dwarf once again retrieves his rations and throws them into the water. The ripples that come back this time are significantly larger, and Gulin quickly scurries out of the damaged stalagmites and into the safety of the sharp stalagmite forest.

Within moments a huge undead sea creature appears. Everyone but Reynnar has had some experience sailing upon the open oceans, and those party members quickly identify the creature as some sort of skeletal killer whale. Flaps of loose decaying skin are visible around the whale's head and fins, though where you would expect to see the belly of the beast there is only large bones.

The creature paces back and forth near the shore, attempting to find the prey that disturbed its slumber. What do you do next?

Reynnar checks that the cloak is obscuring his face, crouches down out of sight, then lights his arrow and looses it at the whale.

Hide: 27

Attack: 22 Damage: 20

Gulin holds the pot of oil in his left hand. Splashing the creature in the water would not do as much good, and he realizes he can't hold both the magic weapon spell and ready the catapult spell...

Gulin uses his other hand and points three stubby fingers at the creature. "Urchraichean!"

A bright steel gray bolt trailing what appears to be molten iron sparks blasts from each finger, spreading out before converging again at the creature. Gulin then makes sure he is behind Caspia, awaiting the next move.

Action: magic missile 12

Gulin mentally commands Avalloc to keep flying with the lantern above the whale, keeping it and the  clearing illuminated as best he can while staying safely above. 

Alone in the dark between two stalagmites, Zee gulps, closing his eyes. “Come on man, this ain’t a good vibe here but this is where they led you. Good things are gonna come from this, it’s meant to be.” He brings his mind back to that beautiful night sky that once inspired him so much. He’d gazed on it for what felt like aeons, and the image of swirling lights had never left his head. 

As he opens his eyes, he’s no longer in the dark. Looking down, he see’s the glow coming from himself, shining stars speckled across the void where his body once was. A shining bow of starlight has appeared in his hand. Instinctively, his doubts subsided, he pulls back the bowstring. An arrow of pure starlight streams towards the whale.

Bonus Action - Starry form Archer Attack: 9 Damage: 6

As the arrow flies through the air, Zee stares at the beast, his face devoid of his regular lackadaisical grin, his eyes filled with swirling nebulas. He thrusts forward the hand that loosed the bowstring, sending swirling  a bolt of starlight at the whale. 

Action - Guiding Bolt Attack: 8 Damage: 15

Moonday Goodmonth 16th, 591 CY

Reynnar's arrow strikes true, driving deep into the skull of the undead killer whale. Magic missile's from Gulin pound into the side of the whale's ribecage. By now the creature is on high alert and deftly dodges both of Zee's attempted blows. While this is happening, the orca lets out a mournful cry that echoes loudly across the cavern. A few small stalactites fall from above.

GM Roll: 13

The stalactites splash harmlessly off in the distance in the water. Caspia's turn remains, but it looks as if the orca is positioned to dive once again deep into the aquifer.

I ended up making a small battlemap for everyone's reference. The red square are the hexes where the stalactites were flattened. Normal movement for hexes within the red square because the obstruction has been cleared. Everything outside the red square is considered difficult terrain. If people would like to be positioned in slightly different spots, let me know. After Caspia goes then it will be the undead Orca, then back to the party in general, no particular order. If anyone want's to be re-positioned slightly ping the discord channel and I'll make adjustments.

"Perhaps, I can entice it forward."

Caspia glows with an eerie blue light, using her ability as an emissary of the deep to communicate with the undead sea creature. She sends it a message, tempting it to move closer to them and the shore. Tritons pride themselves as guardians of the deep and protectors against beasts such as this. Caspia will not let that proud heritage down now even in the surface world.

After sending her message, Caspia shoots the creature with her crossbow.

Attack: 15 Damage: 6

Moonday Goodmonth 16th, 591 CY

Caspia's bolt also sinks deeper into the creature. The creature, while it can understand the gist of Caspia's message, just appears confused. It is unable to assault it's attackers who remain deep within the stalactite forest. You watch as it's mighty tale rises above the surface before the entire creature dives down into the aquifer. From your vantage point back here, you can no longer see it. The huge undead orca appeared injured from your coordinated assault, but not gravely. Having dealt with the steadfast yet stupid will of undead in the past, you surmise that the creature is likely still nearby.

As the creature retreats, Gulin Commands his familiar to keep it in his sight. 

Moonday Goodmonth 16th, 591 CY

Avalloc circles over the underground reservoir holding his lantern in his claws. The undead orca is easy to spot lying off of the coast, but under a significant level of water. As Avalloc hovers there the figure quickly rushes towards the surface, breaching the water in an attempt to trap the bird. But Avalloc's movement is too deft, and he quickly pulls range. It looks like your quarry is lying in wait for easier prey.

"So she's still stalking out there. Avalloc's keepin' an eye, and you all can keep him in sight by that lanternlight. I'm wondering what might be on that island cave she's protectin''... survivors? Whichever magi somehow raised a creature from the deep sea into an undead existence in a relatively tiny underground lake? Cruel fate, really."

He eyes up Caspia, and reaches down into his pack, pulling out a steel shield. With a thick, armor-backed knuckle, he wraps on the shield, making a metallic ping noise. He takes his hammer from its holster. "Lass, do you want to go for a swim? Stick just to the shore, bang on the shield underwater, and brace for impact? My hammer could be use against that creature." 

Caspia smiles ominously, looking more like her warrior ancestors than usual.

"Tritons are always ready for a swim and a battle against a sea creature." She takes off her pack, weapons, and boots so she is lighter and quicker in the water before taking the shield and hammer from Gulin.

The water is dark, but clear

She walks to the shore before entering the water quickly, staying closer to the shoreline for an easy escape. She bangs on the shield so it reverberates in the water and then braces herself to the arrival of the dead orca, using her excellent underwater senses to scan the water around her and listen for the creature's approach.

As Caspia prepares herself, Gulin attempts to hide amongst the standing stalagmites about 10 feet from the water's edge where he can have a good view of her and anything that might approach her.

Stealth 6

Moonday Goodmonth 16th, 591 CY

Gingerly Caspia enters the aquifer. The water is quite chill, likely from the lack of direct sunlight. While the triton keeps her movements slow as to not cause too many ripples, the quick moving underwater object reveals that her presence has been sensed. Within seconds the undead nightmare is upon her.

Undead Killer Whale Attack: 15

The whale breaches the surface quickly closing the distance with Caspia, crashing into the triton. Thankfully her armor and prepared defensive stance protects her from any damage from the assault. It is the party's turn. The undead Killer Whale is currently engaged in combat next to Caspia only 15 feet off the aquifer's shore.

Gulin doesn't feel very hidden, the scales of his mail clinking as he moves into position. Seeing the creature still immersed in water, his plan to toss oil at it seems for naught, so he raises his hand and shouts the arcane words to release another volley of missiles.

Action: Cast magic missile 15

Zee jumps into action, firing a second arrow of light at the whale, keeping himself within the stalagmite forest 60ft from his target.

B.a - Starry Form Archer Attack: 9 Damage: 10 radiant damage.

As the bolt flies, he reaches out to the water. On the surface around the whale, thick tendrils form out of kelp, wrapping themselves around the Whale.

Action - Cast entangle on the area around the whale, trying to avoid catching Caspia in it. DC 14 Str save.

The magic missiles batter into the side of the skeletal orca. Zee release his entangle, expertly keeping Caspia out of the line of fire.

Instead of the normal plant growth Zee has come to expect from this spell in the past, the biolumenscent kelp within the aquifer and underneath the creature begins to quickly grow and attempts to strangle the whale.

Undead Killer Whale Strength Saving Throw: 6

The biolumescent vines wrap themselves around the creature, impeding its movement. Though the creature does appear immune to the normal numbing effect of the kelp.