I'm pulling my hair out trying to figure out how to get this mage weapon.

I keep seeing mentions of The Mage's Gambit orb that does fire and electric damage. The videos and articles discussing the build recommend it, but no one says how to get the damn thing!

Has anyone figured this out?

You would be my favorite and I wish for your favorite treat to always be in stock.

Edit: I got the orb from the lighthouse puzzle island after starting act 2!

Edit 2: Thank you guys for making this the unofficial mage's gambit location finder. You all are out here doing the Maker's work!

Edit 3: I got my Mage's Gambit to legendary thanks to the diligence of the commentors! Please see below if you want to find all iterations of this weapon for your spellblade, these people were kind enough to keep us informed.