If the chain item does not fulfill the conditions by the time step 5: check legality has been reached, the actions taken while playing it are undone and it is returned to the zone it was played from if it is a card.
§ 813.4.b Core Rules PDF (officieel)
§ 813 Reaction
§ 813.4 Some passive abilities may grant a card or ability Reaction under certain conditions. The card or ability does not have the Reaction keyword unless and until those circumstances are true.
