20 Sept 2016
You choose which counters to move as Aetherborn Marauder's triggered ability resolves.
20 Sept 2016
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.
20 Sept 2016
You may choose to move zero +1/+1 counters.
20 Sept 2016
You may move +1/+1 counters from any number of other permanents you control, not just from one.