Rule 806.4

Some passive abilities may grant a card or ability Action under certain conditions. The card or ability does not have the Action keyword unless and until those circumstances are true.

• 806.4.a Those conditions might only be fulfilled while the card or ability is on the chain. In such a case, it can still be…
• 806.4.b If the chain item does not fulfill the conditions by the time step 5: check legality has been reached, the actions…

Official Core Rules