Isskal is the third boss in Drowned Halls. He is a step up from the first two bosses because it’ll require communication from more members in the raid, and has multiple instant death mechanics. Make sure you have 3 interrupters because they will be needed.
Basic Information

Difficulty Level: 4 (Easy)
Health: 1.1m
Hard Enrage Timer: Unknown
Ideal Raid Composition

1 Tank
2-3 Healers
2 Support (Archon, Bard)
4-5 DPS
Strategy

This boss is a pretty good step up from the first two bosses and will help you succeed in killing later bosses in harder raid instances. The boss’s room is a circle and he stands in the middle of it. The tank should keep the boss there the whole fight. Throughout the fight the boss will cast Ice Shard. It will one shot the highest threat target if not interrupted, and sometimes casts back to back meaning you need more than one interrupter. It is not reflect-able. That means you need to take interrupts out of your macros and manually cast them for once! You need a minimum of three interrupters because we had him cast it three times in a row towards the end of the fight.
At 75% (may be time based) the boss said "Go with the current or die!” and began to cast Whirl of Death. Water will fill the room and the current will either move left or right. You must go with the current. Abyssal Trappers with 6k health will spawn during this ability and should be killed while you move because they slow/root players. Pretty sure the slow/root is dispellable. The tank can try and pick them up, but it is not needed. The boss will say "You’re going the wrong way, fools!” and change the current of the water at least once during the cast. Picture of Whirl of Death in-game.
At 25% (may be time based) the boss then casted Glacial Wave. This ability will be a little tricky the first time, but once you see the pattern it will be very easy. He will cover 2/3rds the room in water and after about two seconds the water will erupt and begin to do ~4-5k damage a second. You must move onto the ground that is not covered in water to avoid it. When we fought the boss the sequence which the safe spots were located were Middle safe, Outer safe, Middle safe, Inner safe, Middle safe. Pictures of how the room will be covered. (Blue is Water, White is safe zone) Picture of Glacial Wave in-game. Ability Summary and Recap

Ice Shard – 1.5 second cast that one shots the highest threat target. Must be interrupted.
Whirl of Death – Boss will emote "Go with the current or die!” when he uses this ability. He turns the whole room into a whirlpool and you must follow the direction of the water current or you will take ~1k damage per second. Changes direction half way through when he says "You’re going the wrong way, fools!”
Glacial Wave – Ability that covers 2/3rds of room and changes in a pattern. Deals ~3k damage per second if player is standing in it.
Spawned Adds:
Abyssal Trapper – 6k health. Deals ~1k damage per attack to enemy players. Also slows the player.

 

 

 

 

http://www.riftstrats.com/drowned-halls/isskal/