- Spawned as part of the quest VW Op. 118: Buburimu Squall
- Uses several different types of normal melee attacks:
- Frontal: Single target damage, max HP down (~20%)
- Frontal: AoE damage (double), Amnesia
- Side: AoE damage (triple), knockback
- Rear: AoE damage (quadruple), Stun
- Has a high physical damage taken reduction but takes normal magic damage.
- Has a constant Bio aura (20hp/tic).
- Has Auto Regen.
- Casts all -ja spells and Meteor.
- Has a fairly high Fast Cast trait.
- Can use Chainspell multiple times throughout the battle, first used at 65-80% HP.
- The next usage takes place several minutes after the first one, and will not occur if defeated quickly enough. Fool's Drink should be used to survive Chainspell (the extremely large AoE on Meteor makes it nearly impossible to survive through Chainspell without using Fool's Drink or staggering Botulus Rex).
- Will not use any TP moves or normal melee attacks while Chainspell is active.
- Uses the following TP moves. One or more may have hate reset.
- Chymous Reek Area of Effect damage, additional effect Stun and Choke (Choke cannot be removed)
- Sloughy Sputum Conal damage, knockback, Gravity, and Drown
- Crowning Flatus Area of Effect damage, knockback, and Stun
- Rancid Reflux Conal damage, knockback, Max HP Down, Gravity
- Just Desserts Area of Effect damage, Stun, and Drown (up to 57 HP/tick)
- Gnash 'n Guttle Area of Effect Max HP Down
- <30% HP: Slimy Proposal Area of Effect Charm (~30 seconds) and Dia (over 30 HP/tick), clears negative status ailments on Botulus Rex.
- Botulus Rex has 137 INT, 89 MND, +12.5% Magic Damage Taken, and 40 Magic Defense Bonus
- As of the February 2012 version update, timing weakness triggers properly with TP moves or spells now correctly yields increased alignment/weakness duration on this monster.