Artifact Protection Loop

[xStrayKnightx]

 {Indomitable Archangel} + {Prototype Portal} + {Swiftfoot Boots}.

Play Prototype Portal, imprinted with Swiftfoot Boots.

Play Indomitable Archangel.

Spam Prototype Portal's ability to churn out Swiftfoot Boots for each creature you control, starting with Indomitable Archangel.

Eventually you end up with enough artifacts to kick Metalcraft into gear, giving all artifacts shroud and each creature with a token-copy of Swiftfoot Boots hexproof.