Creature â Troll
When Harvester Troll enters the battlefield, you may sacrifice a creature or land. If you do, put two +1/+1 counters on Harvester Troll.2/3
Players can respond to the enters-the-battlefield ability (notably, while Harvester Troll is still 2/3), but once that ability starts resolving, itâ€™s too late for any player to respond. You donâ€™t choose which creature or land youâ€™re sacrificing, if any, until the ability resolves.