Does Ezreal, Prodigy let you hide cards for free?
Does Ezreal, Prodigy make it so you can hide cards for free? Can you use Seals to pay the hide cost instead?

When you play me, discard 1, then draw 2.
Optional additional costs you pay cost or
less.
Artist: Six More Vodka
Card Set: Spiritforged
Does Ezreal, Prodigy make it so you can hide cards for free? Can you use Seals to pay the hide cost instead?
My opponent said that when I Defy their spells, targets still go through and Ezreal can still exhaust its legend and draw 1. Can Ezreal's legend still be exhausted if the spell is Defied? Also, if I play Ravenbloom Student and Discipline and they Defy, do I get Ravenbloom's on-play effect?
Can Ezreal's cost reduction apply to Sinister Poro's optional "when I attack" energy cost?
My opponent chose one of my units with Deadly Flourish and also used The List's activated ability on the same target. Can Ezreal's legend still be used, since the legend requires choosing twice with a spell and a unit ability?
If I use Ezreal, Prodigy Explorer's power discount on Nami, Tidecaller's optional additional cost, do I need to spend power to play Nami at all? Can I choose not to use Vex's discount when it applies? Does Ezreal's discount let you play Nami without spending power?