A = Aggressive; NA = Non-Aggresive; L = Links; S = Detects by Sight; H = Detects by Sound; HP = Detects Low HP; M = Detects Magic; Sc = Follows by Scent; T(S) = True-sight; T(H) = True-hearing JA = Detects job abilities; WS = Detects weaponskills; Z(D) = Asleep in Daytime; Z(N) = Asleep at Nighttime; A(R) = Aggressive to Reive participants
While Widescan cannot be used to reveal the locations of chigoes, they would be very useful for tracking and avoiding lamiae. There are a lot of blind corners and column-crowded rooms where it is easy for them to sneak up on you.
If you get aggro from a lamia and have a large enough party, send someone to continue killing chigoes so you don't waste time.
The chigoes hit very quickly and you can lose several hundred HP very quickly if you are swarmed. This person should have a lot of HP, high defense, or be capable of healing themselves (preferably with dances, as the quick rate of attack will likely interrupt spells).
A Summoner with a free Carbuncle is very strong in this assault. Time is very critical. Carbuncle will automatically engage and kill the chigoes (because of the enhanced critical hit rate) often before you even have a chance to target them.
A Dancer subbing Samurai for Meditate can be very powerful here. Violent and Desperate Flourishes are one-hit KOs, and DNC has access to Cyclone, an AOE Weaponskill. Waltzes cannot be interrupted by taking hits. If survivability is an issue, /NIN or /WHM (Reraise) can be just as effective, since Steps only take 10TP, and Violent Flourish returns ~5.
Going /NIN so the Lamias don't one shot you can be important. The chigoes die so fast that weaponskills and job abilities aren't even needed. Also, bring Reraise for all of your members so if they get aggroed they can raise themselves in a safe spot after the Lamia kills them.