Geleb Flamefinger casting Hydra.
This skill is used by the Council Members encountered in Act III and even in The Worldstone Chamber in Nightmare and Hell difficulty. It behaves in every way like the Hydra created by a Sorceress. It summons a three-headed beast which fires a volley of Firebolts.
Note, however, that the Council Members will also cast lightning simultaneously while summoning their Hydras.
Though a lone hydra is not so deadly, it can be annoying. However, Council Members are encountered mostly in groups who summon many hydras at a time which can cause serious trouble to players with poor fire resistance. It is generally a good idea to lead the Council Members away from that area and engage them once you are out of the range of the Hydra's projectiles.
Damaging Skills
Fire — Embers • Eruption • Fire Arrow • Fireball • Fire Bolt • Fire Hit • Firestorm • Fire Wall • Flame Circle • Grenade • Hydra • Incinerate • Incineration Nova • Inferno • Meteor • Mines
Ice — Arctic Blast • Blizzard • Cold Touch • Fire Hit (Cold) • Freezing Charge • Glacial Spike • Hoarfrost
Poison — Poison Bolt • Poison Breath • Poison Cloud • Poison Spit • Poison Spray • Poison Sting • Poison Strike
Lightning — Lightning • Lightning Arrow • Lightning Globe • Lightning Storm • Red Lightning Hose • Shocking Hit • Spark Defense • Thunderbolt
Physical — Bite • Blast Wave • Blow Dart • Charge (Berserk Charge) • Cleave • Corpse Cannon • Destructive Strike • Divebomb • Grab • Ground Spikes • Ground Tentacle • Leap • Javelin • Leech-life Ball • Pummel •Quake • Quill Dart • Slam • Snatch • Spine Dart • Strike • Swipe • Sweep • Whirlwind
Magic — Beam • Blade Beam • Blast • Bomb • Bone Spirit • Hellish Projectile • Nova • Tornado • Torrent • Unholy Bolt
Non-damaging Skills
Indirect Attack — Blood Mana • Curses • Mana Rift • Minion Frenzy • Putrify • Spin Web • Stun • Vortex
Spawning — Bone Prison • Festering Appendages • Lay Egg • Mines • Mystifying Growth • Revive • Summon Minion • Totem
Self-effect — Bone Armor • Burrow •Clone • Fly • Frenzy • Heal • Shell • Teleport • Vile Effigy