Invidia is able to summon Taboo Demons. Mr. Bosche states in early Secret Journals that Invidia was taught the techniques to summon Taboo Demons by a "Fallen Angel." It is later revealed that the "Fallen Angel" was Raziel. Invidia uses her abilities at the beginning of his battle against Karsten and Milly.
When she enters the battle herself, she transforms into Pulchra Leo (Latin for "Beautiful lion"), her demon form. Pulchra Leo is an anthropomorphic (humanoid) lion. Unlike most Harriers and succubi in Demon form, Invidia transforms by absorbing Taboo Demons.
Also, unlike most succubi who enter demon form, Invidia's wings shatter prior to the fight with her, suggesting that she is no longer a harrier. Also of interest, most Harriers only have two wings, while Invidia had six, a possible reference to seraphim (highest ranking angels). As a Demon's powers are contained in their wings, it can be assumed from the number and size of her wings that her powers as a Demon were extremely advanced. After her defeat, Invidia is revived through her Taboo demon refinery sigil, becoming a corrupted version of her former self. Though she no longer summons Taboo Demons, she is vastly more powerful in this second form and recovers some strength upon time. In both forms, she attacks primarily using energy bursts (with a cry of "Infinity!") and will teleport to evade attacks.