One card I created was the following: Fighting Spirit 1WW Creature Spirit 2/1 Flying Whenever a mystic spell is played, CARDNAME gets protection from the color of your choice until end of turn
While it does half the damage (only dealing one point of pain at a time) Razorkin Needlehead is also half the cost of Sheoldred, The Apocalype - an infamous creature who has terrorized Standard for ages, and one of the most expensive MTG cards Wizards has put out in recent years
It is much less reliable for final rules MTGPress proxy printing became popular because it solved a very specific Magic problem: players wanted a fast way to turn a decklist into printable proxy TLDR Fan-made Magic cards feel real when they follow the same invisible rules that make official cards readable, balanced, and playable
Some control decks may play a copy of Mystic Sanctuary so thats something to always consider alongside Uro or the odd Snapcaster Although we dont see these decks too often these days, for historic reference: Reanimator: Reanimation targets, Faithless Looting Hogaak: Bridge from Below, Hogaak, Arisen Necropolis, Vengevine, Bloodghast, Gravecrawler, Cabal Therapy Madness: Vengevine, Faithless Looting, Anger NicFit: Cabal Therapy however, really no specific card other than Academy Rector in NixFit builds
The replacement for this function is a wild card system
Thats less than $50 a deck, despite three out of four costing more than that when bought separately