DFOArchive: Prey-Isys Raid Guide [In Progress]

Prey-Isys raid is a 12-man 2 phases operation released on September 24th, 2019.
You need to be at least level 95 with 5,382 Exorcism.
General information such as entry material, raid shop, and rewards can be found at Neople official website.
Note: With 100 cap update, Prey raid rewards have been increased.

Table of Contents

General Concepts

In a nutshell, you and your teams are flying around Skyscraper on a bird called Slenikon.
Slenikon bird is divided into 3 section: Descend (Tail), Body, and Defend/Isys (Head). Depends on where you stand (Head or Tail), Slenikon will drop you off when you pass a particular location.
Slenikon's health will continuously decrease during the raid. If HP drops to zero, the raid will fail. So keep close eye on it.

Phase 1: Nighttime Skyscraper - Outskirts

Phase 1 map is divided into 16 sections. Each section will take Slenikon 15 seconds to fly.
In this map, you will see multiple dungeon indication with different names and colors.
There are 4 types of dungeons in this phase:

The objective of this phase is to clear 4 "Sanctum" dungeons before Slenikon's health reaches zero.
Slenikon location:

Intercepts

These dungeons are randomly generated through out the map, except for sanctum's locations.
If you lose a battle or skip an intercept, then Slenikon will lose a significant amount of HP.
This dungeon is also being generated if you pass and not clear Magic Towers.
Possible Bosses: Fighter Kugai, Heat Researcher Zadracon, Moonbow Eike.

Magic Towers

These dungeons generate Intercepts if you pass and not clear.
If you win, then the Magic Tower will temporarily stop generating Interception units.
Possible Bosses: Aries Kelly, Villainess Greta.

Gardens

If you win, then all your members' Atk. will be increased, and the masked monster portrait will be unmasked and you can tell which dungeon on the map has which boss.
There are 2 total in phase 1 and clearing both, which will grant the raid a total 50% damage boost. (Exclusive 80% buff for Sanctum Parties, Garden Buff 1: 25% boost, Garden Buff 2: 25% boost, with 30% boost in Sanctum dungeons.)
Possible Bosses: Omega Guardian, Cumulonimbus.

Sanctums

The location of 4 Sanctums will always be the same (at mark 1, 5, 9, 13).
Possible Bosses: Golden Wing Tritura, Star Guardian Zodiac, Plunderer Rossol, Celestial Archer Alexandra.

Phase 1 Dungeon Mechanics

Intercepts

Magic Towers

Gardens

Sanctums

Phase 2: Nighttime Skyscraper - Depths

There are 4 dungeons in this phase: Grand Garden, Battleground, Observatory, and Isys. The location of all are always the same.
Defeat Isys will complete the raid.
Slenikon location:

Based on the map above, you will start with Grand Garden (1), then fly to Observatory (3), then Battlegroudn (5), then back to Grand Garden. Every time you will pass Isys in between.

Grand Garden

Battleground

You can only enter this dungeon while another party is in the Isys dungeon. You must meet Isys to enter the Boss room.
If you win, then Isys's Def. will temporarily decrease by a significant amount.
The boss is Red Leg Arketo

Observatory

You can only enter this dungeon while another party is in the Isys dungeon. You must meet Isys to enter the Boss room.
After killing the boss, the next map is a Ballista, activate it by bring its health to zero will launch a bolt and pin Isys down, giving you 20-sec groggy.
Examples of shooting the bolt and Isys being pinned down below.
The boss is Beast Srim

Isys

The party that entered Isys will become Encroached and cannot reenter Isys for a while.
If you clear the Observatory, but fail to defeat Isys, then you will be automatically removed from the dungeon, and your Dungeon Clear count will be increased.
But Isys will not recover the HP that you decreased before you were removed.
If you fail to clear the Observatory within the time limit for the Isys dungeon, then you will fail the dungeon and Isys will recover the HP that you decreased.
If you clear the Observatory, but not within the time limit for the Isys dungeon, then you will fail the dungeon and Isys will recover the HP that you decreased.

Phase 2 Dungeon Mechanics

New Monster Cards

Below are the new enchant cards added with this raid

Guides From the Community

Reasons to do Prey-Isys Raid

Each clear provides 200 Undaunted Determination, which translates into 2 epic souls.
Max of 4000 Undaunted Determination per week (aka 40 epic souls) potentially can be funneled into main character per week.
Cards for Enchantment. Second best in slot after the release of The Oculus dungeon. Refer to Enchantment page for more information.
Prey accessories and special equipment can be upgraded to pre-selected level 100 epic (Fig. 1) through NPC "Administrative Officer Dorothy" in Chest Town (Fig. 2). Figure 1 credit to u/lYongl.