Chel & James remained friends, and after Chel was no longer working for WotC, he would occasionally give James stuff to sell
The most famous is Serum Powder while it's in your opening hand, you may exile that entire hand and draw that many cards, effectively a free extra mulligan
This useful card allows for some energy acceleration once your Lost Zone has reached seven cards
Eldrazi Tron (7.1% of the Winner's Metagame) 4 Eldrazi Temple 4 Urza's Mine 4 Urza's Power Plant 4 Urza's Tower 4 Kozilek's Command 4 Ugin, Eye of the Storms 4 Expedition Map 4 Ugin's Labyrinth 4 Devourer of Destiny 4 Karn, the Great Creator 4 Thought-Knot Seer 4 Mind Stone 3 Glaring Fleshraker 2 Dismember 1 Swamp 1 Vexing Bauble 1 Ulamog, the Ceaseless Hunger 1 Trinisphere 1 Sire of Seven Deaths 1 Snow-Covered Wastes 1 Chalice of the Void 2 Disruptor Flute 1 Trinisphere 1 Tormod's Crypt 1 Ensnaring Bridge 1 Liquimetal Coating 1 Cityscape Leveler 1 The Stone Brain 1 Torpor Orb 1 Walking Ballista 1 Extinguisher Battleship 1 The Filigree Sylex 1 Chalice of the Void 1 Skysovereign, Consul Flagship 1 Vexing Bauble Eldrazi Tron harnesses the iconic trio of Urza's Mine, Urza's Tower, and Urza's Power Plant to enable explosive openings

At the very least one could determine that they are unaltered, but were getting into super cool levels of forensic analysis into determining whether the layers of ink on top match the chemical composition of the ink layers on bottom