Gadwick's triggered ability won't trigger when you cast it because it's not on the battlefield yet.
04-10-2019
wotc
If Gadwick enters the battlefield without being cast, or if it was cast for a cost other than its mana cost, the value of X for its first ability is 0.
04-10-2019
wotc
Gadwick's second ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.