As it turned out, I was completely wrong, and the turn-three Batterskull I was fearing so much doesnt ever happen anymore as most of the time the card is used to fetch Colossal Hammer, and even fetching Kaldra Compleat is often not powerful enough for the format as the card sees little play outside of Hammer Time
Like most Magic: The Gathering cards, the value of Relentless Rats depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Secret Lair Promo)
As many foils of that era, hard to find surfaces without scratches
Flubs loads the yard for cards like Underworld Breach and Mizzix's Mastery with ease
As seen in Frank Karsten's Metagame Mentor from July 13, most of the best Pioneer decks in July were also among the best-performing archetypes at last year's Regional Championships and Pro Tour Phyrexia