Gigantic creatures are spread out over 2 cards, with one card containing the creature’s text box and the other its art, as shown:
In order to play a gigantic creature, a player must have both halves of the creature in hand, and play those cards together as a single creature. The top half of a gigantic creature has the text “1 of 2” next to its title, while its corresponding bottom half shares the same title and has the text “2 of 2” next to its rarity icon.
A gigantic creature counts as 2 cards while out of play, but as a single creature card while in play. Playing a gigantic creature only counts as playing 1 card, and therefore it is allowed on the first turn. After a gigantic creature leaves play, the 2 halves are treated as separate cards again.
Both halves of a gigantic creature have the same title, house, and card type. Otherwise, each half has the attributes printed on it: the top half has bonus icons, while the bottom half has power, armor, and the text box.
If a card instructing you to play or put into play a creature chooses one half of a gigantic creature, that effect will fail. If a card instructs you to play or put into play both halves of a gigantic creature, the gigantic creature will be played or put into play.
Example: Bella plays Wild Wormhole, allowing her to play the top card of her deck. She looks at the top card and sees that it is the top half of Ultra Gravitron. She cannot play that card from the top of her deck (even if she has the other half of Ultra Gravitron in her hand), so the card is returned to the top of her deck.
Any card that would let you play a single card (Exhume, Wild Wormhole, Lateral Shift, Phase Shift, Helper Bot, etc.) cannot play a Gigantic creature because that creature is two cards while out of play. Even if you have the other half of the Gigantic creature in your hand, essentially the effect tries to target a single card, but then fails because that single card cannot be played on its own.
Note from the Arcanists: Some of the cards mentioned in this ruling we believe may have been cited inadvertently. We've reached out to FFG for further clarification from FFG and will update this when we receive more information.Source
Note from the Arcanists: Some of the cards mentioned in this ruling we believe may have been cited inadvertently. We've reached out to FFG for further clarification from FFG and will update this when we receive more information.