Tapped down opponents creature and he was able to untap multiple times with only what was on board, no instants and sorceries were spent to trigger gandalf, no one one counters placed on the Strider. Best I can tell the striders ability to give temporary +1/+1 was tricking the leechcraft into thinking it was a +1/+1 counter, note strider was able to untap on a different turn than the one it was being granted temporary +1/+1 so it was a vanilla 4/4 when it was able to untap. Lost a perfect league off this bug.
