Are the rewards worthwhile? This will depend on progression goals.
With 20-30% Strength up, he’s the Shadow equivalent to Pele and a great budget Shadow Dragon. He also inflicts Blindness, which synergizes well with Nefaria and Orion. Users of Juggernaut won’t gain a whole lot stat-wise, but otherwise, he’s worth picking up.
Although a decent Light Staff user, many players will have better options in Vixel and Hildegarde. Still, Vixel users will want a Poison-Resistant healer for Shadow IO, and her shield Skill competes in magnitude with those of Cibella and Hildegarde. Poison Relief is also included in her shield Skill.
To collect Emblems evenly, stick to Guardian Sentinel Assault: Expert, Thanatos Clash: Standard, and Thanatos Clash: Expert.
For this event, special Endeavors are unlocked upon forging 500 friendship with Felicia. The best way to speedrun this is with Skip Tickets; use up to 10 at once for 200 Friendship on Avenue to Power, or do the daily chests for Imperial Onslaught and Dragon Trials.
With max Friendship, completing the day’s Event Endeavors will reward a daily Summon Voucher. For these, simply defeat the Guardian Sentinel and Thanatos once each, and collect 100 total Blazons. Doing Thanatos Clash: Expert twice will easily fulfill this with roughly 50 Blazon drops per run.
Recommended minimums for collecting the most valuable loot:
Gold: 3000, Twinkling Sand x1
Silver: 780, Astrolabe x1 (580 for Summon Voucher x3)
Bronze: 700, Summon Voucher x3
Emblems required for completing each reward track:
Gold: 5000, Royal Amber Insignia x20
Silver: 1000, Knight’s Testament x1
Bronze: 1000, Knight’s Testament x1
Players may reset the box upon pulling Phantom. Completely emptying each box for materials is optional, but note that the proportion of junk items will increase after four resets.
Parts: Attack the hands to disable his attacks, and wings for better loot drops.
The goal for most players will be to destroy all four parts, which is easily doable with AoE attacks and powerful teams (about 12k Might each)
Thanatos will start a timer known as the Horrorglass. It counts down from 30, at which point the entire team of four will take massive but non-lethal damage. The timer can be evaded in various ways:
When the Horrorglass spawns onstage in front of Thanatos, attack and destroy it to stop the countdown (which runs at 1 per second as long as the glass is up) and regain 5 ticks.
Purple attacks reduce the timer by 5, so be sure to dodge these AoEs. Attack animations can be cancelled by demolishing body parts or shifting the mode gauge into Overdrive or Break.
Demolishing body parts will also give back 5 ticks each.
One of his most notable attacks produces a large purple AoE and four Mana Founts. Veterans of the Hypnos raid will know to destroy these founts and stop the attack. Since there are four founts, each player should run to one and target it with their team.
Obtaining the 90-second Epithet will be tough, but one main strategy for quick clears is bringing Dragon Prep Wyrmprints such as Dragon Arcanum, Dragon’s Den and King’s Countenance. 1400+ Strength is also recommended for the lead character.