Carlos Santana’s show might be dark, but he is not. You feel the rock legend’s light as he talks about returning to the stage at House of Blues at Mandalay Bay. “I feel very giddy about returning to play with a live audience, you know?” Santana said in a phone chat Saturday morning. “There’s something really sacred about going straight to people’s hearts.” Santana’s giddiness is understood. He is finally venturing back to the Strip. “An Intimate Evening with Santana: Greatest Hits Live” reopens Aug. 25, 27 and 29 and Sept. 1-4.