I had to do two Howl's in turn 2 because Surge of Power didn't kill Lilly. My Nexus Whelpling never got swapped in. After Moonfire I used Arcane blast a few times and killed Molaze. Ticker comes in and use Life Exchange and pretty much cleaned up with what was left of Sprite until dead, Nexus finished the fight off!
I did a lot of tries on this one and must admit that a certain degree of RNG is at play here. With this line-up however you shouldn't encounter a situation where you cannot clean-up. Glad it worked for you!