Hero Siege Phantom Leviathan Guide: Season 10's Deep Uber Boss

Season 10’s New Ceiling

Every Hero Siege season reshuffles the top of the power curve, and Season 10 did it with three new names: Phantom Leviathan, Captain Grimtide and Blood Maiden. Launched with Ebontharn on August 21, 2026, the trio now forms the top layer of the Uber roster — the fights endgame builds are measured against.

What the Community Has Documented So Far

An honest snapshot, a little over a month into the season:

• Roster position is settled. Phantom Leviathan is one of the three new Uber encounters, above the classic trio and the modern layer in the endgame progression.
• The fight checks completed builds. Early kill reports consistently describe it as a full-kit exam — damage uptime, survivability and movement all at once, in the pattern of every top-layer Uber before it.
• Kill footage outpaces written guides. The fastest way to see the fight’s actual patterns is video; written documentation lags the patch cadence.

Hero Siege S10 — 3 New Uber Bosses — JuxtAPoser — YouTube

Hero Siege S10 — 3 New Uber Bosses — JuxtAPoser

Preparing a Build for the Fight

Whatever the specific patterns turn out to be, the preparation checklist for a top-layer Uber is stable — it is the same exam every season, harder:

1. A completed endgame build. The new Ubers punish half-finished transitions. If your slots are still mixed Heroic, the Satanic core comes first.
2. Top-of-ladder survivability. Burst that erases under-geared builds is the tier’s signature. The durability discipline built through Hell and Inferno is the entry fee.
3. Practice on the layers below. Routine kills on the modern trio are the community’s standard readiness test — if those fights are clean, the new layer’s mechanics are the only unknown.
4. Loot value runs both ways. The new layer is also the season’s best loot source — peak-tier pieces and the S10 uniques concentrate here, which is why farming rotations absorbed the trio immediately.

Where This Page Goes Next

As the community’s kill documentation settles and hotfixes stop tuning the encounter, this page gains the full treatment: phase-by-phase breakdown, ability-by-ability notes and a boss stat card verified in-game. Until then, the video above is the honest primary source — and the rotation advice below does not depend on the specifics.

The practical endgame stance for Season 10: run the full Uber rotation weekly, let the new layer’s loot fund the build, and expect the fight’s meta to shift at least once more before the season’s end.

Phantom Leviathan FAQ

Can I skip the older Uber layers and go straight to Phantom Leviathan?

The Uber progression gates the new layer behind the lower ones by design — and skipping the practice is a trap anyway. The modern layer kills are the readiness check.

What loot is Phantom Leviathan known for?

As a top-layer Uber, its drops sit at the peak of the season’s item pool — the tiers endgame builds chase. Per-boss loot tables are community-documented and patch-sensitive; verify in-game.

Why does this guide hedge so much?

Because the fight is a few weeks old and the patch cadence is active. Honest hedging now beats confident wrong answers that waste your build’s resources — no invented numbers, only what the community has actually documented.