Here we can discuss what items and artifacts Spike can steal.

Here's an idea for which heirloom each of the eight crime lords have:

The Storm King - The Staff of Sarcanas
Sombra - The Crystal Heart
Chrysalis - Emerald Scarab
Abacus Cinch - Jeweled Unicorn Statue
Cozy Glow - Bronze Medallion
King Longhorn - Golden Bullhorns
Lavan - Indian Dagger
Verko - 18th Century Copper Coin

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Ooh, good ones!

And maybe from Sludge, he'd steal the Blue Monkey!...and make a monkey out of Sludge.