Wickerbough Elder

• WWizards of the Coast2018-12-07
  Official Ruling
  You must choose a target artifact or enchantment to activate Wickerbough Elder's last ability. You can't pay just to remove a -1/-1 counter from it without a legal target.
• WWizards of the Coast2018-12-07
  Official Ruling
  If an effect puts Wickerbough Elder onto the battlefield with one or more +1/+1 counters, its -1/-1 counter and one of those +1/+1 counters are removed as a state-based action before you can activate its ability.

Rulings via Scryfall