Deepglow Skate

• WWizards of the Coast2020-08-07
  Official Ruling
  To double the number of each kind of counter on a permanent, put another counter on it for each counter it already has. Effects that interact with counters being put onto permanents apply as appropriate.
• WWizards of the Coast2020-08-07
  Official Ruling
  You can choose no targets if you don't want to double the counters on any permanents.
• WWizards of the Coast2020-08-07
  Official Ruling
  As Deepglow Skate's ability resolves, you must double each kind of counter on the permanents it targets.

Rulings via Scryfall