Hero card

Key to the Side-Door

Artifact

SpellUsed once: what it does depends on when you cast it

Needs: Legendary

Gives: Artifacts, Card Draw

Not in winning lists yet: read from the card text and the graph

Build a deck with Key to the Side-Door as the hero

Makes it work

Mendicant Core, Guidelight · Krang, Master Mind · Donatello, Mutant Mechanic · Iron Spider, Stark Upgrade · Fizik, Etherium Mechanic · Shuri, Wakandan Inventor · Moon Girl and Devil Dinosaur · Ironheart, Clever Champion

Benefits from it

Emissary Escort · Voyager Quickwelder · Radiant Lotus · Guidelight Synergist · Demonic Junker

Use instead if you don't have it

Heirloom Epic · Soul-Guide Lantern · Rope · Found Footage · Orazca Puzzle-Door · Ghost Vacuum

Cards in the meta that answer it

Countersculpt (Azorius Control) · Inevitable Defeat (4-Color Control) · No More Lies (Azorius Control) · We Say Thee Nay! (Dimir Aggro)