It turns out that this is a little tricky interaction imho. Let's assume that non-active player controls Humility and active player casts Gideon Blackblade. What happens next?
It looks like Gideon Blackblade would enter the battlefield as a 1/1… Legendary Planeswalker Creature - Gideon.
But that's not all.
According to 306.5b - A planeswalker is treated as if its text box included, “This permanent enters the battlefield with a number of loyalty counters on it equal to its printed loyalty number.”
And this one is something that I'm not 100% sure. If Humility affects this part then Gideon Blackblade would enter with 0 Loyalty counters and according to SBA's will be put into graveyard.
So here's my question - Would Gideon enter the battlefield with 0 or 4 Loyalty counters?