The Aquasquirrel is one of the cards from Kaycee's Mod. It is identical to a Squirrel with the exception of having the Waterborne Sigil. It is only found by enabling the Aquasquirrel Challenge in Kaycee's Mod.
Strategy[]
By and large, the Aquasquirrel is a downgrade to the Squirrel despite having an additional Sigil and still being a free sacrifice. The Waterborne Sigil allows opposing cards to attack directly; in other words, an Aquasquirrel is unable to block an attack. (This does not apply to a normal Squirrel from a Squirrel in a Bottle, as Squirrels cannot receive Waterborne Sigils in Kaycee's Mod.)
The benefits that can be gained from playing an Aquasquirrel are either to act as a blockade for cards bearing the Sprinter Sigil on your own side (which a normal Squirrel can also do) or to benefit from the Leader Sigil without risk of being removed by the opponent (whereas a normal Squirrel is vulnerable).
Aquasquirrels are also advantageous to the player if moved to the other side of the board, such as during the Angler's boss fight or by using the Wiseclock. This is because the opponent cannot block damage using Aquasquirrels, either, but also cannot sacrifice them like the player can; additionally, new enemy creatures are prevented from coming onto the board if the spaces they are trying to enter are occupied by Aquasquirrels (even if they are submerged).