On Topic:Let us compare the vanilla (no skill creatures) of Darkness and Water
Black Dragon
10|5 for 10
Ice Dragon
9|6 for 10
(0<HP<6) is worth 0, (5<HP<8] is worth 1
From these stats we can conclude that the stats of Darkness and Water creatures are comparable.
Now let us compare the Infect creatures of each
Parasite
1|1
:Infect for 2
Toadfish
6|4
:Inflate for 5
The difference in Cost - Value between these two is 2
From these stats we can conclude either
Parasite needs a buff on the order of an equivalent of 2 attack or
Toadfish needs a nerf of the same magnitude or
Parasite needs a buff on the order of an equivalent of 1 attack and Toadfish needs a nerf of the same magnitude.
The Current side discussion:
A standard can and has been calculated. This standard can be used to balance the cards within the rounding necessary by the game.