Ovni

Special Attacks:

 * Invincible - Immune to physical damage for 30 seconds.
 * Uses Invincible frequently throughout the battle.
 * Asthenic Fog - AoE Drown (15hp/tick).
 * Vitriolic Barrage - 1000 AoE damage, split between targets in range, and 20HP/tick poison.
 * Concussive Oscillation - AoE damage, Knockback and Weight, blocked by Utsusemi.
 * Torrential Torment - AoE damage and remove all equipment, strips Utsusemi.
 * Primal Drill - AoE damage and Bind, blocked by Utsusemi.
 * Ion Shower - AoE damage and Stun, strips Utsusemi.
 * Fluorescence - Boost.
 * Usually performs another TP move immediately after using Fluorescence.
 * Susceptible to slow, blind, choke, elegy, stun and Poison.
 * All spells can be landed without Elemental Seal with a small resist rate.
 * Immune to gravity.

Notes:

 * Appears to aggro normally once a certain time has passed, or certain conditions have been met on a server.
 * Killed it with PLD RDM WHM BRD 2xBLM THF in 50 minutes (Very slow at end due to high DT-, around 75% at end)
 * PLD-mob; Used Invincible frequently (not sure if timed or %); Melee hits average DMG (80PLD/NIN Burtgang/DRing/Aegis/Valhalla took 100ish DMG from normal hit, blocked 40ish, 200ish in Haste gear)
 * Has Damage Taken-, appears to increase gradually either after every time it 2hrs or with % (THF SA DMG was 150~ at start and 30 at end, took very low dmg from nukes and melee at end)
 * Souleater is ineffective against Ovni.
 * The efficiency of Dread Spikes is seemingly reduced by 95% when hit by Ovni, draining only 5% of damage taken each hit.
 * Both results from Souleater and Dread Spikes were tested with Ovni at 100%.
 * Received 5000 experience points, 1500 cruor, and a temporary Megalixir upon death.
 * Unlike other Yovra, this mob does not possess Luminous Drape nor does it seem to posses any sort of Regen (Status Effect).
 * Rages after 60 minutes.

Possible Weakness Triggers:

 * Rampart
 * Drown

Historical Background
Ovni is the French translation of UFO. It is an acronym for "Objet Volant Non Identifié", or translated as "Unidentified Flying Object".