If a creature has an omen in its text box, you can choose to either play it normally, summoning it as a creature, or to play it as a sorcery or instant, as described in the omen section of the card (the left side of the text box)
However, I don't like the new Mega Hyper Rare cards, the all-gold chase Pokmon cards that were recently added into packs
Many spells return creatures to their owners' hands in blue, so to choose this one in particular, you are either playing +1/+1 counters in a UG deck, a blink deck, or both, and you get an excellent blue board wipe
Targeting your Eldrazi Scion and sacrificing it in response to cast a two-drop and a three-drop on turn 4 with Catacomb Sifter is nice
Alongside each of the twenty Mythic Rare cards that were selected to receive this Secret Lair-esque treatment, serialized copies will also be released to the wild