Without delirium, its a simple Shock-like effect for creatures and planeswalkers
Small divider cards or labeled tabs go a long way
To be honest, you might be better off running Iron Man in the 99 of a Captain America deck, simply because Cap also cares about equipment with high mana costs, cheats equip costs, and crucially adds white to your color identity
As such, Challenger Decks are a way for Wizards to cash in on these cards' equity one more time before they end up close to worthless, which in turn makes them unappealing to reprint in other supplemental products
There's 3 targets to talk to, so put on Jacks outfit, then head on over to Daimon area and go talk to Corse in the Underground Dueling Arena (southeast of Bootleg)
These were all from my personal collection that I had in binders for the last twenty years