Introduction to Coil
The Binding Coil of Bahamut was the first end-game raid in FFXIV: A Realm Reborn. You gain access to this upon completion of a short quest after defeating Titan hard mode. The Binding Coil consists of 5 raids and when first released you were only able to complete each once per week. This restriction has since been lifted.
Turn 1 Begins and ADS
Turn 1 is quite easy compared to the others however if you do not know the mechanics of each boss then you will not win.
Immediately upon entering the area you are met with a boss; ADS. There are two main strategies for this boss. You can either kill the adds that spawn or you can just burn down the boss. The latter is only best if your DPS is high. Whichever strategy you choose there are some key points to be aware of.
When the adds spawn the second tank should pick them up and tank them far away from the boss. This is to prevent the nodes from linking up with ADS and boosting its attack or defense (depending on the node). If you are killing them then the next one will spawn shortly after the first one dies so the damage dealers assigned to these should just stay where they are.
Throughout the fight ADS will use two main attacks. The first is a laser that targets a single player. You must dodge this or take a high damage hit. The second is called High Voltage and you must silence this attack. If you do not then the whole party takes a paralyze status for 30 seconds. You should set up a silence rotation between your BRDs and PLDs in order to prevent this.
After defeating ADS you will fight your way through trash monsters towards Caduceus; the main boss of turn 1. There is nothing complex on the way there and no chests worth going for. The chests are full of medicine only.
Caduceus
The main thing to be aware of with Caduceus is Steelscales. This will increase his attack power. This will stack over time and eventually reach the point where it will kill you, unless you do something about it. While you can not prevent Caduceus from using this ability you can take stacks off him.
Throughout the fight the floor will light up, and whoever is standing on a lit up floor tile will spawn a Dark Matter Slime. By feeding this slime to Caduceus you will remove a stack. It’s not that simple however. You should only have one player feeding slimes, with a backup in case he dies. The slimes will also heal Caduceus based on the amount of HP the slime has left, so you should take them down to around 10-20% before feeding. This ensures the heal is very small. Be careful when feeding slimes because Caduceus will use a highly damaging attack if you stand behind him. He will not spam it so it is worth triggering this, running out of range and then back in with your slime. Or you could have another player do this for you.
At around 2/3 health Caduceus will split into 2, with each part being an identical twin. The mechanics haven’t changed, there are just two of them. What you don’t want to do is tank them together because they will merge and go into rage mode. At this point it is over. So your second tank should pick up the split and take it to the other side of the room. One healer and two DPS players should go with him.
If you were feeding slimes correctly the split should happen at 0 stacks of Steelscales. If this is the case then you can stop worrying about feeding slimes, but if it is not the case then you will need your slime feeder and backup feeder to take one slime each to the Caduceus parts.
The reason for splitting your DPS is because both Caduceus parts need to die at roughly the same time, so if the DPS is split this works out nicely. The first one should die with the second being under 5%, at this point you should use a single target limit break to finish off the other.
Watch a video of the Mog Knights free company on Excalibur defeat Caduceus: