Cordey's cutlass and Regan's hammer manage to land firm spots and the seaweed creature sputters in reaction to the blows. (seaweed: 25 damage)
JIn fires two bolts of Eldritch energy into the mass, while Tasya pulls her shortbow and aims an arrow between the the others at the creature. (Seaweed: 36 damage)
Upon the barrage of blows from the party, the animated hulk of seaweed mass makes a desperate heave, shooting dozens of tendrils out from its bulk. They shoot toward the party but instead fall short as the creature releases a final bellow and its hulk sinks into a wet oozy carpet of seaweed on the tunnel entrance floor. Under the mundane effects of gravity, slimy seaweed rolls and spreads between the feet of Regan, Cordey, Admiral, and Jin.
The tunnel beyond the limp seaweed carpet is dark and foreboding.
Rolls
Jin: Eldritch Blast(s), damage(s) - (1d20+6, 1d20+6, 1d10+3, 1d10+3)
1d20+6 : (14) + 6 = 20
1d20+6 : (14) + 6 = 20
1d10+3 : (10) + 3 = 13
1d10+3 : (8) + 3 = 11
Tasya: Shortbow attack, damage, sneak attack - (1d20+6, 1d6+3, 266)
1d20+6 : (20) + 6 = 26
1d6+3 : (6) + 3 = 9
266 : () + 266 = 266
Tasya: (Correction) sneak attack damage - (2d6)
(12) = 3