With a word from Bixby, Bucky charges forward knocking the bug aside and ending up in S28 just barely. His attack does not harm S27.
Bixby casts his spell and the two centipedes take the full brunt of the damage.
R27; R28: 1D20+2 = [8]+2 = 10
1D20+2 = [4]+2 = 6
Alan's first attack fails but the second attack kills the bug in R27.
The centipedes go.
R26 takes 3 attacks on Triessa.
R27 is dead. (I accidentally rolled his attacks against Alan. Oops. They all would have missed ironically.)
R28 takes 3 attacks on Bixby
S27 takes 3 attacks on Bucky
S26 climbs the wall and ceiling ending up at P27. It attacks Elkhorn twice.
T26 climbs the wall and ceiling ending up at O26. It attacks Coralin once.
click to see the full 15 rolls
Triessa:
1D20+6 = [12]+6 = 18 HIT 1D4-1 = [4]-1 = 3 Fort save needed
1D20+6 = [12]+6 = 18 - 5 MISS
1D20+6 = [4]+6 = 10 - 10 MISS
Alan
1D20+6 = [7]+6 = 13 Oops
1D20+6 = [12]+6 = 18 - 5 Oops
1D20+6 = [12]+6 = 18 - 10 Oops
Bixby
1D20+6 = [18]+6 = 24 HIT 1D4-1 = [4]-1 = 3 Fort save needed
1D20+6 = [14]+6 = 20 - 5 MISS
1D20+6 = [16]+6 = 22 - 10 MISS
Bucky
1D20+6 = [3]+6 = 9 MISS
1D20+6 = [7]+6 = 13 - 5 MISS
1D20+6 = [5]+6 = 11 - 10 MISS
Elkhorn
1D20+6 = [20]+6 = 26 HIT 1D4-1 = [1]-1 = 0 No damage, no save
1D20+6 = [2]+6 = 8 - 5 MISS
Coralin
1D20+6 = [17]+6 = 23 HIT 1D4-1 = [1]-1 = 0 No damage, no save
The fort saves are DC 13. Triessa and Bixby need to make a save or take [roll0] and [roll1] poison damage respectively and become flat-footed.
Centipede at R28 is injured.
Party is up.
Triessa 9
Elkhorn: 1D20+4 = [2]+4 = 6
Coralin 0
Bixby 25
Alan 16
Centipedes: 1D20+6 = [7]+6 = 13