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 — Fire Arrow • Fireball • Fire Bolt • Fire Hit • Firestorm • Fire Wall • Flame Circle • Hydra • Incineration Nova • Inferno • Meteor
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 • Red Lightning Hose • Shocking Hit • Spark Defense
Physical — Bite • Blow Dart • Charge (Berserk Charge) • Corpse Cannon • Destructive Strike • Ground Tentacle • Leap • Javelin • Leech-life Ball • Pummel • Quill Dart • Slam • Spine Dart • Swipe
Magic — Bone Spirit • Hellish Projectile • Nova • Totem • Unholy Bolt
Non-damaging Skills
Indirect Attack — Blood Mana • Curses • Mana Rift • Minion Frenzy • Putrify • Spin Web • Stun
Spawning — Bone Prison • Festering Appendages • Lay Egg • Revive • Summon Minion
Self-effect — Bone Armor • Burrow • Fly • Frenzy • Heal • Teleport • Vile Effigy