Originally Posted by
Thage
This. Wrathion is notorious for shady dealings and withholding valuable information from us, especially when he worked with both factions while fully intending for one to conquer the other, hedging his bets from one to the other as events unfolded. The lies in this case are more metaphorical/symbolic (as bullshit prophecies from Void characters tend to be): in Pandaria, he offered first the lie of hope that you had an ally in him, as he was fully prepared for and, at least at one point in the campaign, actively arranging for the enemy to conquer you. He also offered the second lie of hope that he would be here to aid us during the Legion invasion, where he was instead otherwise occupied. Finally, he offered the third lie of hope that the Void could be resisted with a simple potion, as his boss encounter puts paid to that lie--that he believed it true is immaterial in the grand picture. Il'gynoth never said that he sat at the table and offered lies knowingly and willingly.
In all three occasions, the lie he offers you is hope that is soon dashed against the rocks of reality. Hope being a big theme in the Battle for Azeroth expansion, namely how it is ultimately all the heroes have to cling to as the Void encroaches and Death runs rampant thanks to Sylvanas's scheming and machinations, it's telling that one of the stronger candidates for Il'gynoth's prophecy regarding the boy king not only isn't the red herring we've been built up to expect/suspect, but also one who operates in ignorance of his role in the prophecy, since blind eyes being opened ("open your eyes" being a common phrase to insinuate the listener is being willfully ignorant of unpleasant truths) are another theme running with N'zoth.
But that's just my rum-influenced, quickly-cobbled together train of thought.
Also possible. Il'gynoth, like any proper true Void entity, likely sees all concurrent timelines and, much like Bronze Dragons can, might get the timelines mixed up or offer you information superfluous to your current timeline (like when we're told we basically got the worst possible Garrosh and in another timeline he's the greatest Warchief in the Horde's history, a true dyed-in-the-wool hero who loved and was loved by many, not that that is particularly helpful for us to know that the prime timeline screwed the pooch so badly), in the event it was about Anduin.