Mulligan for Surrender (Shadow Visions), Northshire Cleric or Draws. With coin, I like to Mulligan for Tar Creeper and Shadows Ascendant. I also tend to keep coin until after i use Madness.
Usually I use Madness at turn 5-ish, depending on the match up and what i’ve drawn. I like to use it knowing probability of my curve after i cast, on turn 5 i can still drop a 2 drop and follow it up with a 3 on turn 6 which is the majority of my deck.