The situation:
Iron Pan is in play
Player one rescues with a hero(ability irrelevant)
Player 2 blocks with Assyrian siege army, with another Assyrian in play, targets Player1's good fortress and discards it. Then claims he met the condition on Iron pan for it to be discarded.
Did he?
The special abilities:
Iron Pan: If a Babylonian is in play, negate all protect, immune, ignore, draw and play abilities. Opponent may discard a good Fortress from territory to discard this card. May be activated on Ezekiel.
Assyrian Siege Army: If blocking and another Assyrian is in play, you may negate and discard an Artifact, single color Site, or Fortress in play or set-aside area. Cannot be negated.
I mean technically, Player 2 did discard a Good fortress, but is that sufficient to pay Iron Pan?