2011-01-01 : For the purposes of combat, whether Snapsail Glider has flying is relevant only as the declare blockers step begins. If an attacking Snapsail Glider without flying becomes blocked, gaining control of enough artifacts to cause it to have flying won’t change that. Similarly, if a Snapsail Glider with flying blocks another creature with flying, losing control of enough artifacts to cause the Glider to lose flying won’t change that.