Harbinger remains active too long on transformed cards.

octal9

Harbinger: Give a creature you control Haste and Trample until the end of your turn. That creature is also reinforced four times until the end of your turn.

Emphasis mine.

For testing, deck should consist of Archangel Avacyn, any other creature, and any kill spell.

1) Charge Nahiri's 3rd skill, Harbinger.
2) Get Avacyn & any other creature on the field.
3) Cast Harbinger on Avacyn.
4) Destroy your other creature.
5) Avacyn transforms into Avacyn, the Purifier.
6) Await the end of your turn.

Expected result:
At the end of your turn, Avacyn, the Purifier should return to 10 power.

Actual result:
At the start of your next turn, Avacyn the Purifier returns to 10 power.

As you can see in the image below, Avacyn is now at 50 power during my opponent's turn.



This opens up the opponent to use your ultimate against you. In this case, I had my flipped Avacyn stolen on the next turn by an enemy Saheeli with Exert Influence. (she then casted Uncaged Fury on it which would OHKO all current planeswalkers). I lost a shot at Planar Bridge to this

Screenshot below is doctored to enhance brightness because I was slow to getting a picture:



Please fix, thanks