Aetherborn Marauder

• WOTC Official Reminder Textofficial rules
  Lifelink — Damage dealt by this creature also causes you to gain that much life.

• WWizards of the Coast2016-09-20
  Official Ruling
  You may move +1/+1 counters from any number of other permanents you control, not just from one.
• WWizards of the Coast2016-09-20
  Official Ruling
  You may choose to move zero +1/+1 counters.
• WWizards of the Coast2016-09-20
  Official Ruling
  If a creature has been dealt damage, that damage remains marked on it until the cleanup step. If Aetherborn Marauder takes counters from a creature that has been dealt damage, that creature will be destroyed if the damage is now lethal.
• WWizards of the Coast2016-09-20
  Official Ruling
  You choose which counters to move as Aetherborn Marauder's triggered ability resolves.

Rulings via Scryfall