Damage upgrade -> Puff to Kalder, Raeth -> Coleridge. And Selma -> Dalhia.
Why replace Raeth? Well you already have Taljion who is a better fighter than Raeth at 3*. Coleridge's damage is well worth it and it is a lot easier to connect with a 8 power SOB than a 7 power SOB, hence he is better than other heavy hitters like Selma or Ector.
Why replace Puff? Because strategically 2 damage without any pill manipulation doesn't get you anywhere. If you get into a high pill fight with Puff, you lose even if you win. For low pill fights you have Taljion. You would only want Puff against 7 or 8 power guys anyway- all your guys crush 6 power or below easily. So Kalder's 4 damage is an excellent trade off.
Why replace Selma? Because it's too pill expensive to try to win with a 7 power SOB and no other combat abilities. Selma is *not* an optimal closer. Even if you win with Selma, yes you hit them for 7 or 9, but is +2 pills going to help you win one more round? If Selma only works as the first character you win with, wouldn't you rather have Dalhia who does it infinitely easier? If you need a closer in Piranas, that's why you have Coleridge, Ahkab or Raeth.
Well, which cards to use is a matter of personal preference, but one thing's for sure: Piranas have good abilities and an excellent bonus, but you gotta make sure they can deal enough damage, especially when their only DR is permabanned. There's nothing more annoying than winning 3 rounds and still losing the game!