Deceiver of Form

({C} represents colorless mana.)
At the beginning of combat on your turn, reveal the top card of your library. If a creature card is revealed this way, you may have creatures you control other than Deceiver of Form become copies of that card until end of turn. You may put that card on the bottom of your library.

Oath of the Gatewatch

Oath of the Gatewatch Promos

Any noncopy effects that affected a creature you control, including ones that modified its power and/or toughness, will continue to apply.

If a creature you control becomes a copy of the revealed creature card, it’s neither entering nor leaving the battlefield. Any enters-the-battlefield or leaves-the-battlefield abilities won’t trigger.

If applicable, creatures you control copy the printed values of the revealed creature card. They will retain any counters they had on them. Any Auras and/or Equipment that were attached with them will remain so.

You may put the card on the bottom of your library in any of the possible scenarios that could occur with this card. It doesn’t matter whether the card is a creature card or not. If it is a creature card, it doesn’t matter whether you chose to have the copy effect apply.