The Lord of the Summer Haze, whose real name is Christiva, is the Sage of Fire. She is a young woman with reddish-black hair.
She is corrupted by the Diva of the Twilight and forced to battle Isaac. After finding that Twisted Wand Castle is barred off, Isaac battles the Lord of the Summer Haze again, this time rewarding him with the Lost Magic of Fire.
The Lord of the Summer Haze, like the other Sages, does not give her real name. Her real name can be discovered by selecting her in a mutiplayer battle.