Decomus Castle has been a battlefield for ages. The Noble Hybrid Warriors spent years fighting the usurping Gigantes' Royal Knights over the right to the castle's grounds.
Woons Swordwind possessor of mystical teleporting powers is put in place by the Nobles on a clearing in Shrouded Valley, waiting to teleport adventurers to the castle gates, so they can help getting rid of Gigantes's crew and kick them out of the castle's grounds.
Infiltrate the castle and find out what secret dangers lie within. Will Gigantes simply let you eliminate his army and faithful servants? How far in his evil schemes will he go to stop you? Remains to be seen, because this is a battle of strength and will, the winner takes all!
As long as you follow the basic principles, tankers tank and make him face-sideways so that the other melee can attack at the back of him so both can be healed without the worry of the healer being attacked. And also moving across the bridge when he uses Monster Power.
Once that's done, just attack him normally and ranged class keep your distance from his Overshadow skill. It hurts a lot. A Good tip especially for those ranged users, when the boss is about to use Overshadow he usually 'pulls' the characters within range to him so while he's 'pulling' you just move away from him and his 'pull' skill is nulled, it doesn't work always, but if you time it correctly, it'll work almost everytime. Also, healers be light on your feet to spam your debuff's and make sure to spam your Heal over Time (HoT) skills. It'll help buffer the boss' DoT debuffs.
Soon Sharlach will be dead for he's no match for your teamwork.
Healers SPAM HoT's and keep your distance so you can remove debuff and remember about moving when he 'pulls' you. Be sure to move/lure the boss out of his sanctuary (Power of Light) when he uses it, as you'll just be wasting your skills/attacks while he's inside it.
Fast n' Reckless
This method you skip all the mobs surrounding Zaraz and just lure him and attack him but with the risk of drawing attention of other mobs in the area.
Slow n'Steady:
You can guess this one. Kill all the mobs surrounding Zaras. Either way works, so go ahead and choose which best suits your style. Zaras is straight forward deal your damage and keep on going while Healer spams HoT and remove debuff's. Once he reaches 50% of his HP he will start to use Mental Discipline, so beware and stay cautious as he sometimes does swiping skills that attack players who are at both his sides or attack players that are directly front and behind of him. So a good tip for ranged users is to stay in a position that is diagonal to him. Soon enough, Zaras will be dead.
Like previously mentioned, if your going to lure the boss or tank it, get your healer to cast the shield on you so that you can by-pass the stun skill that he first uses.
The thing about this boss is that if you have another melee character attacking from the back, don't be surprised that the boss will suddenly attack you on sudden intervals. So, heals keep watch of the HP of your party members.
The beginning is pretty straight-forward, deal damage and healers spam HoT's and remove debuffs.
Once you get him to 50% make sure to put most of your focus on killing those summons as they usually target your healer first and a healer that's stunned/silenced is pretty much useless. So head my warning.
Each time when he spawn a summon, just ignore the boss and kill the summon then go back to focusing your primal attention to him again until he's dead.
You can never predict what this boss will do so just keep your main focus on dealing damage and healers doing your job, healing. AND make sure to kill those summons when he spawns them. If you follow this, you'll have no problem defeating this boss
As long as you remember not to attack him while he's using Ice shield, you'll easily win this boss, but don't be too cocky and jump the gun, he still have quite a few powerful hits, but with a well-oiled team you'll have no problems.