Boss Essence

Boss Essence is a stackable summoning component — the raw material you collect to forge a boss summoning key.

Each of the four bosses has its own flavour-matched essence: Echidna (green), Lamia (purple), Hephaestus (gold), and Thanatos (dark purple), with art that glows brighter as your stack grows. Collect 64 of one boss's essence and the inventory sweep auto-forges them into a single Boss Key for that boss — see Summoning a Boss.

Where to get it: dropped by Shades & Wraiths (tier-mapped to the boss), caravan master, warlord and escort kills, and from the Erebus Cap pit ladder. Lower-tier sources lean toward easier bosses; the hardest essences come off the toughest kills.