Shield Lob -> Flash -> CoS -> Flash spam -> RB combo if needed

All you need to know about PLD AOE enmity. If you have WAR/PLD, obviously the WAR will be tanking the spiders, but with PLD/PLD you'll want one AOEing and one RoH comboing everything (+ his own CoS) - that way damage is split pretty evenly and no back and forth aggro happens.