Druid Amalgam

What — A single ~55-ft necromantic monstrosity built from all ~42 slain druids of the Druid's Grove, fused into one body (heads, torsos and giant arms protruding everywhere, sharing "one giant set of lungs"). Raised by the teenage necromancer Dreadweaver Corpsefortune from the corpses beneath the grove and risen from the grove's pond at his death (Session 47).

Threat — Deadly / near-TPK. Shouldered aside 80-ft oaks; its escalating hymn would have wiped the party had the fight run one round longer (Session 47).

Observed abilities (Session 47)

• Multi-arm slam — an action delivering several 15–21 bludgeoning hits per round at 30-ft reach.
• Hymn of the Ancient Ones — a DC-15 Wisdom-save psychic hymn whose damage doubles every round (5 → 10 → 20 → 40 → 80) until it "sings you all to death."
• Mass Goodberry heal — a one-time ~100-HP self-heal (100 Goodberries).
• Graft — can absorb a downed creature into its mass; it grafted Silithane's 1-HP familiar bat and gained blindsight 60 ft.
• Gap: no stated AC or total HP (whittled to 4 HP at the kill); slam hit count not fixed.

Resistances / immunities / weaknesses (Session 47)

• Immune to psychic (41 brains) — Silithane's Shadow Blade / Booming Blade did psychic-immune damage, though the blade itself still cut.
• Near-immune to spell-breaking — holds 41 druids' worth of spell slots, so Fenric's spell-drain stripped only a trivial fraction per hit.
• Resistance to nonmagical weapon damage — bypassed by silver: Thalia's silvered whip and Silithane's silvered short sword cut through the resistance.
• Weak to fire — fire spreads across the whole shared mass of druids; the 48-damage Fire Shield retaliation that ignited one arm raced through every fused druid and killed it.

Tactics & behavior — Lurches ashore and closes to melee, hammering with multi-arm slams while building the doubling hymn toward a guaranteed party kill; grafts downed creatures to extend its senses. Mindless aggression, no negotiation or retreat.

Disposition to the party — Hostile; a necromantic construct with no will of its own, built to make "intruders witness the success of the work."

Status — Dead / killed (Session 47). Whittled to 4 HP, it slammed the fire-shielded Lash; the 48-damage Fire Shield retaliation immolated it and all its fused druids, destroying it a heartbeat before its next (40/80) hymn could resolve. No PC died (Lash survived the slam, 18 of 25 HP). Magra afterward cut it back into 41–42 individual bodies for burial.

SUMMARY: A 55-ft monster of the grove's 42 fused druids — multi-arm slams and a doubling psychic Hymn — psychic-immune and slot-rich but weak to fire; killed in Session 47 by a Fire Shield retaliation seconds before its hymn would have wiped the party.