My fastest for general PvP is:
Note that the lethality check for poisoned happens in a different step than the damage, and occurs afterward. You can use this to finish off the rear troops with the spell damage and deal lethal to the next one up, but I’ve also seen it skip the lethality check on the second-from-the-rear troop if the rear troop dies from the initial damage (at which point the third-from-rear gets the lethal poison check). I do know that if the entire enemy team is poisoned and within kill range of his spell damage, you will kill the entire team when he casts. You can also strike right through barriers on poisoned enemies and kill them. This may or may not have been an intended part of his design, but since the other target lock issues (eg., Kraken, Khorvash) have been repeatedly brought up and not fixed, this one might here to stay as well. I actually think he works much better like this than “on paper” as it gives his one shot a bit more bite.
I had mixed results from the team in the original post. Boards dry on blue/purple/green really hurt your starting position to the point where it is almost impossible to catch up. Combination scale guard/marsh raptor taps rarely nets a kill except on the first enemy and only if I skull them first, otherwise, I need a Scale Guard and two Raptor casts. If you can get a strong starting position versus the right team, you can methodically take them apart, but every explode or Raptor kill spawn risks setting up the enemy team for a death cascade. As an example, I handily beat some troll/kraken at least a few times, but about half my fights are an uphill battle, even versus random cobbled together one and two trophy fights, because the colors I needed just werent on the board, or Marsh Raptor ate a multicascade and died early. A single poison immune troop also ruins all your synergy (though you would be aware of that and choose a different team instead). I’m sure this team would work much better out of endgame PvP (skill bonuses wise), where you could double tap enemies rather than them lasting through three casts and Scorpius could just be a huge finisher once you have softened and poisoned everyone.