5th boss seems to be pretty much a ranged tank and spank?
For the most part it is. If anyone but the tank gets close, the boss channels Wrathful Release which pretty much wipes the party. Melees beware!
When the fight starts, a sword appears and should be clicked by the highest dps in the party. This enables him to hit the boss with normal damage, regardless of his armor being on.
Eventually blue text will pop up saying "Energy comes from all round and surrounds the undead corpse. You see that the energy is making the weapon the monster is holding become even more deadly." When this happens, the boss will reset aggro as well as drop his armor. The tank should click the armor, as it grants a large amount of hp as well as the ability to pick up hot babes. Cooldowns should be popped at this time.
At the start of every 'dps phase' 3 randomly chosen people will have 5 seconds to back away from the party. The debuff and graphic is similar to 4th boss in WA's 5k dot. After 5 seconds, those chosen will explode for a large amount of damage and anyone close will also take damage.
"The Skeleton General retrieves the magnificent armor that was previously his" signals the 'tank phase.' Once again he will drop aggro.
It seems that the boss randomly hits for 38.5k when switching from tank to dps phases and vise versa.
Abyss Blow hits everyone in the party for 52k and is usually followed up immediately by Whirlwind Sword Breath that randomly chooses one person to hit. He also has attacks called Curse Strike and Suicide, but we don't know what causes them yet.
Most importantly, everyone is given a debuff at the start of the fight which will reincarnate that person as a Death Curse if they die to anything but the purpley explodey aoe. The Death Curse is tanky and hits for a pretty high amount of damage. It also rules over Halloween Town when Jack Skellington is away visiting Christmas Town or making cameos in the Kingdom Hearts franchise.
In short, it's a healer intensive fight.
Edit: It's all good, scooter!