MTG Salvation

I play the Draconic Domination Pre-con. commander deck and I edited it, putting cards in and out. Doing so, I put Sunbird's Invocation in the deck. (Whenever you cast a spell from your hand, reveal the top X cards of your library, where X is that spell's converted mana cost. You may cast a card revealed this way with converted mana cost X or less without paying its mana cost. Put the rest on the bottom of your library in a random order.) The deck has a lot of cards that say "Dragons cost 1 less to cast. For example, The Ur-Dragon's Eminence ability causes Crosis, The Purger to cost one less to cast. Making his mana cost 5 instead of 6. Would this trigger Sunbird's Invocation where X is 5 or 6?