Ballista is a plain Siege unit with 6 strength and no special ability. It does one job, adding solid points to your back row, and it does that job well in the early Northern Realms deck.
You don’t have to hunt for it. The card is already in the Northern Realms starter deck Geralt gets when he learns gwent in White Orchard, and only one copy exists. Keep in mind that Torrential Rain drops every non-hero Siege unit to 1, so a Clear Weather card in your deck helps protect it.
If you are working through Collect ‘Em All, this is one of the cards you will own from the very start.
