Here are my thoughts...
dawn to dusk,
Nourish me.
Arum,
Icicle for 2 + (18/2) = 11 damage, putting you in 4th position, moving MeowMeowCat to 2nd and Linkcat to 3rd.
MeowMeowCat,
Grace me, shielding me for 2 damage and moving you up to 1st position, dawn to 2nd.
Linkcat is
swapping to Entropy, remaining in 3rd position.
ProBacon, Arum is now directly above you, so use
Mimic from 5th to
Icicle for 2 + (15/2) = 9.5 = 9 damage, moving you to 7th, fabian to 5th and UTAlan to 6th.
fabian771,
Quicken iancudorinmarian.
UTAlan, from 6th,
Icicle for 2 + (14/2) = 9 damage, putting you in 8th, 101 in 6th and Tim in 7th.
101, use Acid for 4 damage and a DoT of 2. Your position won't change until after the boss moves.
Timdood3,
Pinpoint with whatever guesses you want.
flyingcat,
Fortune (subtract 1.)
mettas,
Strike for 3 damage, or swap to another element. Not much else for you to do until you get below 25HP - Fire doesn't seem like a strong starter.
Aves,
Viciousness on me for 10 (shielded for 2 by MMC's Grace), moving you to 20th for a massive Subterfuge next round.
Espithel - big one here.
Tactics on MeowMeowCat and myself. Moves me to 1st to tank, moves MMC to 19th for massive Grace shields when needed.
ji412jo,
Viciousness on me for 6 to 19th position.
kinkykitten624,
Nourish dawn to dusk.
iancudorinmarian is using
Fortune (subtract 1.)
RootRanger,
Hope on me.
killsdazombies, same as Root -
Hope on me for the full heal.
I'll
Guard dawn to dusk for 3.
Kuroaitou is using
Quicken on Linkcat.
I think these are our best moves for the round. This puts me in the leader position to tank as Earth, sets up all our Light healers at the bottom of the list, with our two Darkness elementals right at the bottom for big damage next turn. Feel free to point out anything you disagree with.