If your first going for pill manip I would recommand changing Blood for Dahlia and Spycee for Tula(tula is great in later rounds) if tula is banned Bonnie Ld, if you dont have her then play spycee or Puff mono, secondly you got 4 two stars... This is very bad when you draw all of them(and yes it is going to happen)
I would say change Oflgn for Dagg or Lovhak if your poor, and then change a two star for either Tyd, Sunder, Ulrich
I like both Bloodh and Raeth in your preset. They are solid characters for 4th round, which is what you want to pair up with a Vortex half. Bloodh and Slimian are the only 5* Piranas that are fully functional 4th.
I don't like Spycee in your preset. You should have Piranas that you want to win with. Spycee isn't a Pirana that is great to win with because he only does 2 damage. The only "lose" Piranas you might consider instead are Ulrich and Bonnie. I would prefer Ulrich because your Vortex does what Bonnie does... give you pills when you lose. Ulrich fits on 4 quite nicely- if you lose with Vortex on 3, you have enough pills to win with Ulrich on 4 for 5 damage.
You might consider Neloe. Your matches are going to go to 4 rounds most often so you should have some DR.
You might drop Raeth for Tyd- Tyd is almost as good of a fighter on 4, especially if you are losing with Vortex on 3. The only downside about this move is Tyd has nothing if your hand has him as your sole Pirana.
You have a good 12* 1/2 for Vortex.
Vortex and Piranas don't complement that well in general though.