Aluren

• WWizards of the Coast2004-10-04
  Official Ruling
  The mana cost of the creatures being cast is still the stated cost on the card, even though you did not pay the cost.
• WWizards of the Coast2004-10-04
  Official Ruling
  You can’t use Aluren when casting a creature using another alternate means, such as the Morph ability.
• WWizards of the Coast2004-10-04
  Official Ruling
  You can’t choose to cast a creature as though it had flash via Aluren and still pay the mana cost. You either cast the creature normally, or via Aluren without paying the mana cost.
• WWizards of the Coast2004-10-04
  Official Ruling
  Aluren checks the actual printed cost on the creature card, and is not affected by things which allow you to cast the spell for less.
• WWizards of the Coast2008-08-01
  Official Ruling
  If creature with X in its cost is cast this way, X can only be 0.

Rulings via Scryfall