From Final Fantasy Wiki

Diabolos is the Rank II Flying Non-elemental Esper in Final Fantasy XII: Revenant Wings. Its normal attack, Nightmare, deals damage to a single foe and may inflict Sleep, and its special attack, Gravity, takes 25% of a single enemy's HP.

Battle

Final Fantasy XII: Revenant Wings Enemy
Diabolos
		Str	Mag	Stm	Mnd	Affinity	18	Melee
		12 - 507	15 - 609	13 - 607	15 - 510	Type	Flying	Paramina Rift Summoning Melee
		Atk	MAtk	Def	MDef	Nature	None
		18 - 141	18 - 167	3 - 151	3 - 127	Weak Against	None
Level	1-99	Speed	AtkSpd	MvSpd	Sight	Resistant to	None
HP	230 - 1,022	12 - 804	20	.654	3.5	Immune to	None