Cactair is a unique monster in Lightning Returns: Final Fantasy XIII. It can be found in the Dead Dunes, within the sandstorm blocking the passage to the Oasis Lighthouse. This enemy counts as a Last One.
For Lightning to confront the Cactair, the player must remove the sandstorm protecting it. Using a Pilgrim's Crux item on the nearby stone will disperse the sandstorm, allowing the player to engage in battle. The Cactair spawns only once per playthrough.
Except for some circumstances, the Cactair sustains only a single point of damage from all attacks. The player must outlast it by chipping away at its health one point at a time. The Cactair will occasionally execute its 1000 Needles attack, which will fail on the first two attempts, but will make contact every time after.
Given that the power of player's abilities is irrelevant, and the fact that staggering the Cactair does not increase the damage dealt, the Sparrow Comb is recommended, as it will reduce ATB cost of Aerora; the multiple hits offered by each cast makes this spell preferable. Alternatively, Magnet has lower ATB cost, no finale animation, and is also a multi-hit ability that prevents Cactair from attacking with his melee attack. However, it's only obtainable from monsters. The player should mix spells with Light Slash, which can deliver two hits at a time with a double-bladed weapon. Inflicting Slow also delays its actions.
The Martial Monk garb's Whirlwind Kick ability is also tailor-made to rack up the hits in this battle.