| Forbidden Impulse |
When put int the battle zone, a specific number of seals are put around the corners of the card.
While it has seals on it can't attack or do anything, but on stronger cards the impulse doesn't leave the battle zone. When you put a creature with a command race that has the same civilization as the impulse into the battle zone or use various card removal cards such as Liberation of the End, you put a seal from the Impulse into your graveyard. Once all of it seals on the impulse are removed, it flips onto the Forbidden Creature side.
Note that a Forbidden Impulse is counted towards the 40 cards in your deck, so don't accidentally pack one more card in case if you want to pack them in your deck.