2019-11-12 : A creature is modified if its text has been changed to modify its abilities, if it has gained or lost any abilities, or if a counter or an effect has set or changed its power or toughness.

2019-11-12 : A creature isn’t modified if its controller, color, or types have been changed.

2019-11-12 : A face-down permanent’s “printed” power and toughness are 2. It has no abilities.

2019-11-12 : A token’s “printed” abilities, power, and toughness are the values it was created with.

2019-11-12 : Certain kinds of cards (such as flip cards, adventurer cards, and double-, triple-, and four-faced cards) define alternative characteristics for those objects under certain circumstances. Using these alternative characteristics doesn’t count as being modified.

2019-11-12 : If an effect only defined a * or ? symbol in a creature’s power or toughness, it isn’t modified.

2019-11-12 : Most copy effects will cause a creature to be modified, although in some unusual cases the copy effect will leave it with the same power, toughness, and abilities. For example, a Runeclaw Bear that becomes a copy of Glory Seeker will, oddly enough, not be modified.