For Turn 4, I'll give more details for our strat that doesn't use any ballad.

P1 - Pop shroud right of the bat, and keep tracking engage time so u won't kill spider too fast. (each phase = 1 min unless u kill faster).
P2 - I let MT tank only knight, dps tank soldier at MT side. I heal OT Knight+Soldier (Seal). MT & DPS is handled by SCH.
P3 - (Seal) Duo heal since our group has no problem with dps. Side note that DN has WS off GCd that might be suck if solo heal (3 attack in a row)
P4 - Holy x2-3 -> Shroud
P5 - (Seal) MT on DN (heal by SCH), DPS tank soldier @ mid OT tank Knight. (I heal both OT & Soldier)
P6 - MT tank DN (P5& Eat Spider) + Knight heal by SCH. OT tank DN (P6 & Eat Spider) + Soldier heal by WHM. Pop shroud after first few heals to reduce aggro & regen some MP + both tank hallowed.
DPS order is LB rook -> soldier + dot Knight -> Knight -> DN (P5) @ MT -> DN (P6) @ OT.
WHM prepare backup Benediction on MT if needed in case SCH screw up. After soldier is down, WHM rest MP with regen on both tanks and cure I only. After DN(P5) is down, everyone stack up at whm and medica2+cure3 when enrage. (shroud is back to pop reduce aggro from cure3)