If I play a spell and it's countered by Defy, will it still count towards Legion?

Yes, a spell that is countered by Defy still counts toward satisfying Legion requirements.

According to RiftJudge FAQ #9461:

  • Legion checks whether a card has been Finalized on the chain, not whether it successfully resolved.
  • When you play a spell, it is placed on the chain as a "Pending Chain Item."
  • Once you choose targets and pay all costs (including any additional costs like Deflect), the spell becomes a "Finalized Chain Item."
  • Players then have the opportunity to play Reaction cards, such as Defy.
  • Because Defy is played after the spell has already been finalized, the Legion condition is already met. Even though the spell is subsequently countered and removed from the chain (per Rule 425.1.a), the requirement for Legion has been satisfied for the turn.