one piece tcg royal blood booster box OP 10 Sleeved Pack led by Donquixote Doflamingo One Piece TCG [OP-10] Royal

It's got the 'snake heads branch off a snake body' model, but instead of snake or dinosaur heads, the Balduvian Hydra's multiple heads look like

GU, Tap: Double the number of each kind of counter on up to two target creatures and/or artifacts you control

Similarly, if an effect creates a token and puts counters on it (such as a Fractal token) the additional token will also get those counters.

So your rating is in line with my own experience playing with and against Library

It fits nicely into builds like Adeline that want to fish out cards like Myrel or Boromir, or even in Giada Angels, where the counters can buff Angels large enough to Station quickly