Purify out,
I don' t think so, if the opponent have poison damage, purifiy is a good prevent. And if you want fast kills, you can use shockwave with freezes.
If you want only water. Just upgrade your toadfish in puffer fish. But cause you won't kill creatures, flooding could be interesting.
If the opponent has heavy poison, you are as good as dead, trying to fish that one card in 30-card deck.
If the opponent has light poison (arsenic in rainbow), you might as well ignore it and replace the purify with hard hitter.
If the opponent has no poison, well...
Shockwave + Freeze is only useful against massive creature. It's nearly always beter for Freeze + Inflate.
Seeing that he only included one Puffer Fish, it's safe to assume that he don't have enough money. Hence the water/air version.