Complete Dreadsail Reef Guide for ESO

Tideborn Taleria will attack the player with aggro (the tank, ideally) and rotate a series of mechanics that are on timers and health thresholds. Details on each of the mechanics can be found below. 

When Taleria opens a portal, if there is any Winter Storm (see mechanic below) active, Taleria will dispel it to allow players to reach the bridges.

Players will have 60s to bring the Channeler mage in the portal down to 50% of its health before it casts Dreadsail Ascension and wipes the group. In veteran, there’s no limit to the number of players you can send and typically anywhere between 2-4 is recommended.

Note that you don’t need to necessarily finish all portals if you have enough DPS to kill the boss before Dreadsail Ascension happens.

Mechanics

Arcing Slash

Light attacks from Tideborn Taleria. They hit twice, with physical and cold damage. Everyone in the frontal cone will take part of the damage. There’s a faint visual cue when the attack happens to show how wide the cone is.

This attack places a dot Soaked Wound on the target and every attack refreshes its duration.

Coral Slash

Heavy attack from Tideborn Taleria. It hits twice, with cold and physical damage. If roll-dodged, it creates a water spout that deals low damage. 

Rapid Deluge

Rapid Deluge will place a detonating bomb of 19m radius on the 5 closest players to the boss that detonate after 6s, dealing damage in area.

It can be blocked and shielded, but the correct way to deal with it is to dilute it!

How to survive Deluge: Right before it detonates, dip in water (you need to be swimming, dipping your toes is not enough!) and let it explode in the water. You will take no damage. But stay too long, and the Slaughterfish will kill you.

Rapid Deluges that explode on the land also damage players that are swimming.

In Hardmode, 8 players get Rapid Deluge instead of 5.

Slaughterfish Damage

This is oblivion health-scaled damage. Staying in water for 4.4s deals more than 100% of your max health. Note that you also take some damage from Diluted Deluge. It deals 2.5% of max health per stack, with stacks increasing every 550ms. 

Sea Behemoth

The Sea Behemoth will spawn every 60 seconds - several of them can be up simultaneously if they are not dealt with. They spawn on top of the main tank - the player with aggro from Tideborn Taleria. In hardmode, it spawns every 45 seconds instead.

Health: They have 5.7M health, and 8.3M in Hardmode.

The Sea Behemoth will do a series of light and heavy attacks on the off-tank, but most importantly it will cast Arctic Annihilation, an area of denial slam that deals damage at the beginning and afterwards when staying in it. All the areas created by a Sea Behemoth will disappear when that enemy is defeated - as opposed to the abomination slams in Flame Herald Bahsei - for example.

Sirens

Sirens, Leimenids, Lemonades, witches or however you call them. Two will appear around the atoll, attacking players at range (Frost Bolt) and periodically casting “Lure of the Sea” on a player. That player will be feared and drawn to the water in the center - that deals damage. If you lose control of your character - break free. Make sure you have enough stamina to break free before the mechanic happens. 

Maelstrom

Every 30s, the boss will stop attacking and it will spin its blades for 6 seconds dealing damage over time to everyone within the atoll at around 3 ticks per second. The ticks of damage can be blocked and/or dodged, but they will drain your resources.Stack, and let the healers out-heal it. Make sure you do not leave the group to go to the portals as this mechanic is about to happen.

Winter Storm

A wall of tornadoes appears centered on the hardmode banner location and spins clockwise or counterclockwise. During the first few seconds after spawning, the wall deals no damage, but afterwards, crossing it or even dodging through it will be lethal. At the same time, there’s a smaller damage over time on the whole party.

In hardmode, two walls of tornadoes on opposite sides (180 degrees from each other) will rotate - reducing the space you have.

Crashing Wave

Three waves will appear fixed on the map, and an additional one that tracks and follows the main tank. After a given time, everyone in the area takes damage. They are dodgeable and blockable.

In Hardmode, there will be an additional tracking wave following the off-tank.

Channelers debuffs (mages)

Each channeler comes with a dome centered on them of a specific color that applies a debuff on players inside it. While the portal is active, its corresponding debuff affects everyone on the atoll and in the portal. 

Venom Evoker (Green)

Sea Boiler (Yellow)

Tidal Mage (Purple)

Channelers health: 3.88M.